Yeah, that's kinda the idea. But I'm worried about preserving messaging integrity: if you just let that person set an option to never see reactions at all, then his coworkers will be sending reactions which he won't see, which will probably lead to conflicts ("why didn't you acknowledge that you saw my message?" "I did! I sent a thumbs-up!" "I've disabled reactions, so you need to type out these acknowledgements to me." "Fuck that!" -> HR has to get involved)

Basically, the anti-reactions people are going to be angry no matter what, because the rest of the world isn't doing messaging the way they want.