I think the badge isn't for the reaction, but for posting comments whose text is solely "+1" or "<thumbs up emoji>"
Oooo I see, well in that case... badge away!
Side note - it would be if Github squished all of those down into reactions and next to the reaction added a line saying "we squished the following comments to reactions (show squished comments)".
No pun intended there with the word squish.
YouTrack kind of has support for that https://www.jetbrains.com/help/youtrack/server/Workflow-One-... and I thought they muted the notification email for the comment, but I couldn't find any evidence to support my recollection. Similarly, I thought they had a whole series of "low value comment" handlers but also similarly I wasn't able to find any evidence of my hallucination
I would say the "thumbs up" on a comment is one of the most helpful things on Github, it telegraphs that a comments is usually the fix for something, if we didn't have loads of people doing the "thumbs up" reaction on comments, we wouldn't effectively have stack overflow style answers in comments.