mls - I completely understand why one would think that. But he's not really a BO per say. He's an older man who used to have horses and had to sell them all due to a hip break. He was keeping one mini there for a friend, and my wife and his wife work together and they thought it would be good for both minis if we moved ours there, too. Our mini was alone and on a dry lot, their mini was alone on a big pasture, and both needed a friend. He throws them some grain in the evening and keeps the water filled and that's it. It makes him happy just to have a horse, even a mini, around still.
Still, I am prepared for him to say no. If he does I'm going to ask if we can keep my mare to the safer part of the pasture instead of letting her out on the whole thing, even if that means the gelding and her are separated by a couple strands of fence for a few weeks.
MHFQH - No worries lol, I've dealt with alot of ponies/minis in my time and I know better than to throw them out on an all you can eat buffet and hope for the best! She was out on about 5 acres 24/7 when she was younger and maintained weight nicely, but now that she's not growing as much I know her metabolism has changed :) She's also on a ration balancer that my vet loves for founder-prone animals so I think we can keep her under control. Especially now that she's going to start some conditioning!