This is total BS, if she had a basic open water certification, and some experience, and carried the proper redundant equipment, she should have been allowed to dive.
She did not have any redundant equipment.
Have you thought out the logistics of diving doubles for routine diving on Bonaire? Are you going to switch out cylinders between fills? I don't think the system is set up to quickly refill your doubles. I've only spent 6 weeks on Bonaire in the last year and a half. I'm sure doubles are used for tech diving, however, I've not seen a single diver with doubles. In fact, I've not seen a single diver with sidemount, either single or doubles, which would be considerably easier to deal with.
On the subject of the doubles tank rentals.
I rented a set of doubles from Dive Friends. They did ask me if I was tech certified or did I just want to rent a set of doubles. I got the impression that they would not rent doubles unless you were tech certified.
At the time, they had just taken over the Den Lamen dock, so they had no compressor access. I went to the cliff facility in hamlet oasis to have them filled in the morning and afternoon. It was good in a way because I could get thinner mixes of nitrox by alternating air and x32 fills.
Half of the people on our last trip in January dove two tank sidemount. It was way more convenient than dealing with the doubles for me.