It may have been blocked because of local sports contracts.
Not sure of the game or your location to know if that could be the issue.
Same thing happened to me in DC area. This is clearly a mistake on Verizon's part, as NBA games on TNT and ESPN are never blacked out. The only blackouts are on NBATV, when that game is also being broadcast by the local sports channel, in my case NBCSports Washington (formerly CSNMA).
I would love an explanation (and apology) from someone at Verizon. I called support and was told that because this blackout happened in the past, there's nothing they can do about it. Surely there is some technical log that shows this message screen being activated at 10:30 EST last night for TNT.