As positive an update as there can be! My brother (aka Jim), his wife (aka April), and I video chatted a couple of days ago now. Long story short: they already knew, and he's toughing it out like a champ. They've been showered with support from all sides, which probably makes him more uncomfortable than ever, but he seems to at least appreciate the good intentions.
We took a couple minutes alone, and Jim seems more worried about the extra stress this inevitably puts on April than about himself, for better or worse. He told me he knows that it's all bull, and that it doesn't feel quite real. I flailed around trying to ask him to please call if that ever changes, since I can reality-check with him from the Era of Eve the Ex. I hope he would, though I'm not sure how realistic it is to expect that or to assume that he wasn't just putting a rosy lens on it for me.
April was able to tell him first. One of Jim's friends called her soon after the article caught fire to check on them. She looked it up and talked to him right away. It's no one's first experience with Eve's choices, unfortunately. April's amazing, and there really couldn't be anyone better to process this with him.
They ended the call because the kids were climbing him like a jungle gym begging to play Legos, so they're already doing a great job helping him focus on the things that matter.
Thank you again for all your help, good redditors!
TL/DR: My brother's wife had already talked with him, and they're both tough stuff in the face of adversity. Hooray for family!
EDIT: This isn't a parable about how poor, innocent men constantly have their lives ruined by horrible women through random accusations of assault. That parable is a bullshit narrative concocted by cis, straight men who don't know how to cope with company at the top of the hill. This just happened to be the situation we were in. Needed to say that. Cheers!
EDIT 2: Ooh, instant hate mail. (Seriously, MassimoL?)