Maybe Sam Altman said nicer things about Donald Trump. Maybe he promised that he would not revoke their API keys when Hegseth directs the military to seize ballots. Maybe he's jockeying for position to take over the government when AGI hits.
Ultimately, I don't know how much the specific reasons matter. Pete Hegseth must be removed from office, OpenAI must be destroyed for their betrayal of the US public, that's all there is to it.
1) Another OpenAI cofounder (Brockman) gave Trump’s superPAC the largest ever individual donation of $25m.
2) Trump’s son in law (Kushner) has most of his net worth wrapped up in OpenAI.