Even if I take as granted the advertiser problem is solved, it seems like Twitter has still been hurt by much more than having a controversial CEO:
1. Musk took on significant debt in order to buy a company already slightly losing money. Because of this, it's not good enough for advertisers to just "come back", they need to greatly increase their ad spend on twitter.
2. Twitter's attempt to find an alternative revenue source (the significant changes to Twitter Blue) seem to have largely failed.
3. The disaster with verification is driving away some of Twitter's most important posters that generated content on the website for free.
4. Twitter's reputation as an employer has plummetted and they are presumably not attracting anywhere near the amount of talent they previously did.