Freedom of speech isn't an inexorable right but a perogative. Abuse it, and it will be taken away because in doing so the powers at be would protect the freedoms of the people that your abusive speech tries to undermine.
Regardless of how admendment rights are moderated in a public context, though, the plantif must have signed some sort of TOU to be on the PSN, which expressly prohibited whatever he did which resulted in his ban. So, he should have been well aware of the consiquences to his actions. He has only himself to blame for his unsavory fate, and in suing I hope he gets a painful lesson in the harsh reality of life beyond his sheltered existance.