Selling FSBO - buyer's agent now wants to be transaction agent

[Kay March]

I'm selling a rental house as a FSBO. An agent brought me a buyer. The buyer's agent says that in order for the transaction to proceed, he will transition from being a buyer's agent to being the transaction agent with a 4% commission. I'm assuming that this means the buyer will no longer owe him a commission and I will owe him a 4% seller's commission. Am I correct about that? I've sold as FSBO before, but I always paid 3% while the buyer also paid 3%. I haven't done it the way this agent is proposing to do it, so I'm wondering what others might think about it.