Herman explained to Tommy UK all that Calab had told him. Tommy really wanted to believe that what Calab said was true. If it was true then his father was still alive but trapped beyond time in a rift between worlds. Indeed it might have ben his father who got Tammy and Tommy out of the rift they were in. If that was true he might be able to save his father.
On the other hand he had adventures with the man in black. He had shown up whenever Pigeon Falls needed help and had always been part of the solution. He had learned to trust him. Now he wouldr have to forget all that and plot against him.
Further if Calab was telling the truth then Tommy UK had helped seal the opening through which help was coming for Pigeon Falls. The town's destruction would be his fault. It was worse than that as the destruction of all mankind would be his fault.
But he had to decide. If the man in black was evil then Tommy should try to reopen the doorway. If the man in black is good then Tommy should destroy the talking heads. He went back to reading the driblet.