As Elon Musk’s capricious tendencies continue to spark chaos at Twitter, hundreds of thousands of users have signed up for rival services, including, apparently, Musk's ex-wife Justine. The 50-year-old author declared Friday morning that she had registered for Post, one of those emergent adversaries. In October, the former couple reportedly attended a Halloween party together, suggesting they were still on friendly terms. Some of Justine’s recent tweets, however, suggest distaste for Musk’s antics. “So let me get this straight,” she wrote on Dec. 2, around the time Musk was reinstating previously suspended users, such as a prominent neo-Nazi. “We are now supposed to step into the ‘marketplace of ideas’ to debate + discuss if Hitler behaved poorly, or if women should be ‘raped + locked in cages’? Because these are conversations the culture needs to be having?”