I'm not afraid of losing my gym and I don't plan on giving it away that soon either, However due to my lack of internet access atm and that he had asked me for the gym first gives me more then enough reason not to except your challenge.
Plus seeing as how you so easily threw away the poison gym after just winning it doesn't show me that you would be a very good leader to take my place. Who's to say you wouldn't just throw it away days after taking it and leave it abandon because you "decided you didn't want it anymore".
I'd rather something I care about that I've had since the beginning of gyms on the site be taken care of by someone I trust, know is very good at battling, and is on a lot battling. You'll just have to accept that, there are plenty of inactive gyms that could really use a leader right now.
Check them out?