Firstly, I'd like to point out that you aren't FORCED to always not contract wrists. But just like in TW if you want to achieve a tier you must show you're competent and capable or playing without any advantages and that you can actually play well under certain conditions. After you achieve your tier you can do whatever the hell you like (in TW people just comeback anyways because it's fun). So if you want to contract wrists after you get T1 then go ahead.

Secondly, I'd also like to point out that the best players in the mod actually don't contract wrists. Watch for players like Tman, SainTD and players such as themselves. To counter contracted wrists with a relaxed/extended/held wrist opener, simply grab their actual wrist joint or they forearms. What happens is that they can't use their wrists at all and you'll end up forcing their elbows to dq from too much force. It's just another tactic and you'll feel like much more of a better player if you succeed.

snake is simply trying to broaden your horizons and teach Team Aikido members how to play with more finesse and fairplay. No one else helped him in doing the tiers, so how should he know what you want out of it?
He did say that suggestions are welcome for different requirements/skillsets for each tier and how you can rank up by playing either way.

Going back to my first point, if someone can define a new set of skills/requirements for tiers, then you can play however you'd when you apply to any tier (contracted wrists and the works).
Suggestions are always very welcome, so please, get involved with the org and help out.

edit:

I doubt you'd be able to join Team Aikido because of getting DMs. ;d Good players are shown by their impressive saves and their movement/counters, not by getting dismemberments/decaps (although sometimes dismemberments/decaps can be funny in aikido ;d ).