I’ve pointed a typo in Stephanopoulos’ name to Irene Colthurst in her bio, and she did not immediately excoriate me. 🙂 Yes, it’s a confrontational tactic, but not everyone will take offence.
A less risky strategy is private message, if the user has them enabled.
A really roundabout way if they don’t, as you point out, is to find a mutual friend—someone they follow who you can message, and get them to let them know.
But I gotta say, I would not consider answer commenting to point out a typo rude, as long as your comment is appropriately deferential…