Just wanted to touch base about all the comments regarding how briefly he's been diving for and having no business diving trimix. Although I do not agree at all that you need to be diving for many years to move into technical diving, I do agree that to be a proficient trimix diver in 1.5 years would very hard to do unless you had essentially no job and did nothing but train (not vacation dive/teach OW divers) all day.
I did not get a chance to meet the deceased, but for comparison in terms of time limitations while diving with a highly demanding job, I'm an ER doc working a busy schedule and still dive 3 times a week. It is definitely possible to dive frequently even while holding a demanding job. To be fair, the only reason I'm able to do this though is because I do not have a wife or kids and live in a state where I have >20 lakes within 1 hour of me.
For full transparency, I've been diving for a little over a year and a half. My pathway is a little different than some as I got into diving specifically to wreck dive. It had always been something I've wanted to do and I'd been interested in, but in the last few years I finally acquired the means and time to actually pursue it. I didn't really care about vacation diving or seeing fish. My goal was to dive wrecks in the great lakes - deep, dark, and cold. Admittedly when I started however, I had no clue what kind of work and training that would actually take.
In my first year I did my OW, AOW, drysuit, nitrox, deep diver, night diver, and finally wreck diver courses spread out throughout the year. I dove (haha) head first into diving and right from the start was diving multiple times weekly, logging about 100 dives in my first year of diving. Around where I live are tons of lakes, some deep and some shallow, all very cold, dark, and silty. My weekly diving was not for sight seeing. I fell in love with diving itself and the challenge of skill mastery and dive execution in harsh conditions (for some reason executing a dive in 0 visibility floated my boat). Of the 100 dives my first year, only ~15 of those were vacation/high visibility warm water dives. Most of the time after work me and a dive buddy would just head to any local lake and get in off the boat launch, exploring, practicing boyouncy in <5 foot visibility, and practicing skills. I feel that I advanced quicker than most because I had a hard goal I wanted to reach and was literally training as much as I could to move towards it, kind of like someone intensely training for a sport. When I wasn't diving or at work, I was reading about diving or talking about diving. I got lucky and got plugged into some technical diving mentors early and began reading/obsessing over physiology, theory, and technique (being a science nerd), and dreaming when I'd finally take the step into doubles/deco diving.
Early on in my second year of diving, I completed AN/DP, which is the level I am still at as I didn't want to move on before I thought I was ready. I'm still diving in the michigan winter 3 times a week in lakes around here that aren't frozen over. Since it's winter and cold as balls (lack of a thermocline/no warm water to ascend into/deco in is tough to deal with), most of my dives are short deco dives just to keep my skills up and train. Luckily I have really good mentors to dive and train with. As much as I want to take advanced wreck for penetration and I want to take trimix this summer, realistically I don't see it happening because even with all the work I'm putting into this I don't think my skills will be there for me to personally feel safe to move into trimix. Before in my first year I felt like I was flying through things and there wasn't much to learn from specialty to specialty, but then I made the leap into doubles and then to decompression which was humbling and more work than all of the diving I had learned before it. I think by the end of summer since it's a good 6 months from now I'll probably be ready to start advanced wreck since we are talking another good 50+ training dives from now, but no way I'd be ready to do trimix.
This is all coming from someone with a full time demanding job and an unnatural and unhealthy obsession with wreck diving doing regular diving each week specifically for training. Could I have physically completed all the certifications the deceased completed in this amount of time? Yes. However as someone who has been working their ass off learning and training and is completely obsessed, there is no way someone could be PROFICIENT in that level of diving. I'm being a little narcissistic here and tooting my own horn but diving actually comes naturally to me and I can quickly pick up skills/technique. Being a science nerd for a living, the theory/physiology fascinates me a comes naturally to me as well. However what it took some time to frustratingly realize is that as I'm diving (haha again x2) deeper into the rabbit hole and my dives are becoming riskier, it's taking exponentially more experience to feel confident that I'd be able to handle anything and everything that could go wrong/present itself to me. Experience isn't something that can be rushed. Although you can rush and obtain every c card, sometimes It's hard to realize your limitations and weaknesses, step back, and slow down.