Those are frivolous arguments (and she’ll likely be stuck paying her ok’d employers’ legal expenses) unless she was fired for one of the exceptions expressly listed in the law - there are only a few of those and political beliefs/public speech are not one of them.
1. You can't dismiss anybody merely for posting on a platform that you don't like, especially if she's been posting the same stuff on Twitter for years without]t as much as a squeak from her employers and what she posted this time was exactly the same on Twitter, Gab and Parler. Plus her employer made it clear the employer was making a far left political statement, whereby the employer is on a jihad to promote Twitter and destroy Gab and Parler. The employer didn't even bother to hide her arrogance and venom.
2. This a clear case of violation of her civil rights. She needs to get a good lawyer quick.