As a dungeon master using 3.5 editon would you let (Player Character ) PC use clever ways to avoid disaster?

I would probably inflict a disaster upon myself before playing AD&D (except 1st edition) as it went from “inadequate” (2nd Edition) to “Utter crap” (4th Edition). You really need to broaden your horizons :p

However, as a GM, I’ve seen players try stuff like that, and it rarely works well. Any decent GM will see it as a challenge, and will find interesting workarounds. For instance, resistance to disease doesn’t do anything if someone injects a gallon of acid into your veins, nor does it protect against “cookie cutter” nanites that explode and rupture every blood vessel in your body, sometimes with enough force to damage bystanders.

Personally, I would allow it, simply because if the player gets out of hand, I can come up with a more interesting way of ending them. GMs can be at least as devious, and often are even more creative about breaking PCs than players are when it comes to trying to break the rules.