I try to take people, even strangers at their word, until proven otherwise. I bump into deco regularly on an aluminum 80 even on nitrox. Of course as soon as I see and anticipate it about to happen, I move up in the water column. I was on the Spiegel just a week and a few days ago, definitely went into the deco but I also moved up immediately and by the time I reached the mast the boat was to and reached 60 feet, did a stop and it cleared into the yellow, by the time my 3 minute safety stop completed I was green on the bar. I consider this to be routine. If push came to shove and I wanted to get bent I am quite sure I can do it with an 80cf tank and then some. Of course that would be very stupid.
If a diver, like our OP does not understand or agree with the dive plan, again, the time to discuss that is before the dive. I realize though that unexpected things happen. More than once I have been told we are going to do blah, blah and not drop below max of 100 feet blah and immediately saw the guide at 130 plus. Years ago I told my wife to stay with the guide, in Cozumel, I was infatuated with my new Nikonos III, I looked around, after being told we would stay above 100 feet and sure enough he and my wife were at a good 150. I nearly had my head explode I was so mad and rushed down and grabbed her up. Now I tell her to stay with the guide if I leave her a minute but I also give her our own briefing and max depths and turn times etc.
It is good the OP questions these things, I would probably do the same. Some places are indeed known for "cowboy" diving. We want to have fun, not get hurt and spend our vacation in a chamber (do they have a chamber?). Cowboy Diving, Yahooooo, then have a cowboy in SCUBA riding a deco computer graphic, you know that would make a good tee shirt, a few nice ideas lately.
N