I would say publicly dissing the boss is cause for firing... even with the ridiculous Civil Service protections that let Peter Strozk be busted to near zero, but not let go. “cause” is the magic word. It’s not free speech when you directly harass.
If Strozk was as high as they say he was, Deputy Director, that’s SES...there’s no civil service protection. He’s been kept on because he’s been cooperating with the investigation.