I never keep my reg in when I hurl. I've never ever inspired water after, either.
I get that some people have a phobia about removing their reg, but I certainly don't. I've been pukey sick under the water three times. Once was CO poisoning. By the time I figured that out, it was breathe, puke, breathe, puke, ad nauseum. (See what I did there?) I was diving Venice Beach Fl, looking for Meg teeth and still came up with 6 and a mammoth spit tooth to boot. One time was the flu and I was guiding. Yeah, it was rough, but this would happen while at depth. I had a family of three I was guiding and I was feeling like I had died already. I was at the Winch Hole and would feel a swoon coming on. I would find the closest rock that wasn't live coral hold on, tuck my head to my chest (so's not to gross them out), spit out my reg and let 'er fly. The Yellowtails loved me and swarmed the three of us... even when I was dry heaving. At the end of the dive they gave me the biggest tip I ever got for guiding and they called me the "fish whisperer". They thought I was praying for the fish to come when they swarmed me. 2 phreakin phunni! I never figured out the third one. It wasn't as bad as the other two and since I wasn't working, I was able to call the dive pretty quick.
Yeah, timing is everything here. But, it's simply not that hard to pull the reg out, do your business, rinse your mouth out and then plug 'er back in. Like the mask on the forehead, this 'rule' you have to keep your reg in your mouth is nothing but a myth. If you want to keep your reg in, then do it. Do what's comfortable for you.
I know, that there will come a time, when I'm on my rebreather that I'll have to be the fish whisperer. You can be SURE that I won't be throwing up into my loop when that happens. Yes, I have a BOV, not a DSV, so I can act like it's a regulator, but I don't think I'll be doing that. So, I'll be keeping the loop/valve clean and since it's a rebreather, I'll be bailing ASAP. If anything, I've learned that being sick underwater reduces your ability to suss things out. It's one thing on OC, but quite another on CC. When in doubt, bail the eff out and call the dive.