Elon Musk, ’s new overlord, promised advertisers that he wouldn’t turn the social network into a “free-for-all hellscape.” But many big marketers didn’t believe him — and hundreds temporarily halted their spending on Twitter amid concerns that Musk’s ownership would present “brand safety” risks. The concern: that their ads could show up adjacent to hate speech, misinformation or other objectionable material. Musk, a self-proclaimed free speech “absolutist,” has reinstated thousands of Twitter accounts that had previously been banned, including those of Donald Trump; neo-Nazi Andrew Anglin; and Andrew Tate, who has been arrested in Romania on human trafficking and rape...