We got Ava about a month ago and we're still having problems catching her in the pasture, but once caught she's a dream to work with. Yesterday we were able to pick up her feet and clean them out, walk her over a tarp, put a tarp on her, put a saddle blanket and very light saddle on her, pony her on a trail ride for an hour, bring her in a river on that ride...not bad for a horse that hadn't been handled prior to a month ago.
It wouldn't be a problem as long as it wasn't too heavy. I start getting mine used to a little weight applied to their backs and stuff. As long as they don't act like it's heavy it's shouldn't be a problem.
I don't think they led her around, just put it on her. Had they trotted and stuff, I could see where it might be a problem, but I am pretty sure they just sat it on her.
I think it is a major problem, at 6 months old??? Yikes. You aren't even supposed to start green breaking them until around 2.5 years. I just think it's better to let a baby be a baby and not rush them.
She looks like a complete darling. The more you work with her with catching, the easier it will get. I bought a colt a few years ago, whom you could NOT catch EVER. By the time I was done with him, he would come to the gate when called and would put his head in the halter on his own. Keep working with her, because it will get better. You can pm me if you want and I give you some pointers.