He left the company last year.
Palmer's big donating spree happened after his firing, and those later donations still didn't go to alt-right causes/candidates, just Republican ones.
[edit: The post I was side replying to has been deleted. Sorry if this post now makes less sense.]
Uhhh what now?
Describing it as a $10K donation for a single anti-Hillary billboard misses the parts of the story that caused controversy at the time. The controversial aspects included his connection to Milo Yiannopoulos and moderators of r/The_Donald, and their connections to abusive online behavior and white supremacist rhetoric.