What happens if he refuses to accept that block, and another miner creates a block without that transaction, and he accepts that. Won't this create a soft fork, and it will be up to other miners to decide which fork to run with.
Miners can decide not to include a transaction into the block they want to mine. I think there was a mining pool that proposed to censor transactions from from specific addresses in the past but nothing like that was later done. I do not think this can lead to a soft fork. Also there is nothing yet like a node to reject a transaction if the transaction is valid. No censorship in bitcoin network.