The use of the word "threatening" makes it sound like someone just made the story up to have something to publish. That way the story doesn't lose credibility whether it turns out to be true (no one shows up) or false (oh, gee, they worked it out). I think it was probably inspired by the lack of celebs at the Golden Globes, so they're focusing on the next awards show fiasco in the making. I'd be more surprised if Jon was threatening to actually show up for the Grammys. If memory serves me correctly he hasn't attended since 1991 when he had 3 nominations and handed out the record of the year award with Diana Ross. Richie, Dave, and Tico have attended, but Jon hasn't.