Big Mark fan, here, and I tolerate Cheryl, at best. It's been almost 2 years since he would've actually retired (his contract ran until early fall '22), and is hopefully enjoying his time away from TV. There is almost no reason for him to still be retweeting the Cheryl haters, and doing so "hurts" his legacy more than the incident he was dismissed over. For a guy who has said he's ultimately glad to be out of there ("that place will be a car wash in 5 years"), he sure can't seem to put it in the rear view mirror.
ON THE OTHER HAND, he doesn't need professional help. I'm confident none of us here have medical degrees to actually recommend that. He's just a 70-year-old man who's a little crusty about how his career ended, which is valid. As much as I don't think he should be doing what he's doing on Twitter, I'm guessing he's also within his legal right to do it, and is otherwise quiet about the whole ordeal.
Ultimately, we're making a bigger deal out of this than anyone in his replies. Until he and Cheryl sue each other over NDA breaches or whatever, him retweeting Cheryl shade every once in awhile probably isn't worth mentioning. Honestly, I'm glad this thread didn't exist when Kevin Roy was having his actually-concerning, in-need-of-mental-health-intervention Facebook meltdowns.