I would find it slightly to moderately insulting that I was not allowed to wear a Ghillie suit. As far as being a Heat Casualty; that is the risk you assume when doing anything and not hydrating. Someone who is slightly out of shape without a ghillie suit who doesn't hydrate is just as likely to become a victim of heat stroke.
Above all; it's like anything else in life. It seems like they bring "safety" in a lot; but this is what waivers' are for. Any host in their right mind uses a waiver; and that waiver should state something about injuries, death, etc. that eliminates any blame from the other attendees and event holders, unless there is gross negligence (E.G. They told someone they couldn't bring water with them and then the person died of heat stroke).
Also; I think it's kind of hilarious; to me I play the game for the realism; having done this work in real life I would find it propondrous to do it without all my equipment; a ghillie suit is included in this.
Overall there shouldn't be a "Leader" of any major airsoft group. It should be a "Council" so to speak; of members who have an unbiased view of things. Yes safety is a high priority; but if minor safety implementations make a major detraction from the fun of the sport; then why play?
To those without Ghillie usage being an option; use your other availabilities. If they won't let you wear concealment, make it. Take up a good position and use an e-tool to dig 5 inches deep into the ground the size of your body; have a buddy cover you back up with foliage and natural vegetation. After all; it's just using mother nature right? Show them you can follow their rules and still be undetected. (Note that you don't need an E-tool; a hasty concealed fighting position can be accomplished in less than 5 minutes.
At the end if/when they get frustrated with not finding you just say "Hey, I felt naked without being able to use all my equipment... so I had to cover myself with something... and well; dirt was readily available."
Just my 2 cents on the situation