You are ascribing a lot of human reasoning and emotion to corporate entities they they just dont have. Gratitude is not part of their decision making process. Instead, they might attempt to use past behavior to predict future behavior when evaluating an outlet for their marketing budget. They arnt going to prefer an outlet that occasionally burns advertisers, even if the benefited from it once.
Most of the companies/ceos doing this over the past few weeks do know better. That’s why they didnt say anything earlier. The reason they would be publicly taking this stance now is that they either expect to be rewarded by the incoming administration, or they hope to avoid punitive retaliation.