I wouldn't call you saying something ignorant and then getting schooled on it a "debate", but you do you.
The developer, Drew Harrison, is out of Seattle, Washington. Sucker Punch is operated out of Bellevue, Washington. Washington is an at-will employment state, meaning the company can fire Drew at any time, with or without cause, and with or without notice, as long as the reason is not illegal (such as discrimination, retaliation for whistleblowing, exercising legally protected rights, etc.).
In Washington, a private company generally can terminate an employee for speech or conduct it considers damaging to its workplace culture, reputation, or values. This includes mocking an assassination or celebrating someone's death, even if done outside of work. This does not infringe on freedom of speech since, as I stated earlier, freedom of speech is protecting an entity from government reprisal, not consequences from private entities.
I don't know where you got your law degree, but I would ask for a full refund on that.