If that initial statement about not caring about the ad's context were true the advertising companies wouldn't have torched Youtube's as revenue 5 years ago because explicitly their ads were played on unsavory content. It turns out they do care, probably not for moral reasons but presumably because some bean counter actively calculated that they'd lose more than they gained from such perception of being associated with Fringe viewpoints.
The problem seems to be that large companies don't want to be associated with certain 'deplorable' content but at the same time, they don't want to vacate those spaces and thereby allow other companies (I.e. competitors) to target and acquire those 'deplorable' customers... They'd prefer it if those 'deplorable' spaces simply did not exist on these platforms.
If this is the case, it is anti-competitive. Companies should not prevent new markets from forming around growing new ideologies and communities (regardless of how deplorable they find them). Companies have to choose; stay true to their current ideology and miss out on new market opportunities or embrace changing ideologies and risk losing some of their existing user base.
