Every case I've ever followed, has at least someone, or several someones, that simply cannot accept the person they know/love, is capable of the thing they're charged with. I can completely understand that. I've had the unfortunate experience of knowing someone who did the unthinkable (not murder, thankfully) contrary to literally everyone's opinion that such person "could never, would never!" do such a thing. And yet, they did. Stuff happens. People do vile things sometimes and it's dang hard to accept that the person they thought they knew was indeed capable of doing the worst thing.
In such a case like this, I can only assume those still supporting Barry genuinely believe someone else, in some way, disappeared Suzanne. It really does take some serious logic juggling to explain away the burned journal in the fireplace, the Broomfield alibi, the staged bike, the trail cams being turned off the same afternoon Suzanne was last heard from, and the loads of other evidence.
jmo