The issue is to get to the ROFR being exercised, the seller and the buyer have to sign a sales contract which is submitted with the ROFR request.
If the sales contract was created by the closing company, chances are it also did a certain amount of research to verify details for the contract.
So a small fee to pay for the above is reasonable. That's a good chunk of work.
Such things should be discussed up front when engaging a closing company.
PS. While the buyer normally pays fees, I would negotiate the deal that all costs shift to the seller if the RIFR is exercised.