I would say you should include it. Possibly look to the disclosure that FM provides in a Runtime Solution as an example of the direction to go with the verbiage.
It doesn't sound like he's releasing a runtime. Though we don't know that for sure.
If it's just a FileMaker file; well, I am not a lawyer; but I don't see why that would be necessary. Anymore than releasing a novel in MSWord format.
I know it is not a runtime. It was an example.
I do not think it is needed but it would not hurt.
I don't think it is necessary to include anything about Filemaker. I have seen Open source license agreement that state Filemaker is a registered trademark of Filemaker Inc., then I have seen license agreements without it.
Tim Dietrich has a few open source databases include with license agreement. timdietrich (Tim Dietrich) · GitHub He has used license agreements with and without filemaker name. FMEasySignature, I believe mention FM in the license agreement but FMEasySync did not.
If you sell FM with the free copy of your database then it might be wise to mention FMI in the license agreement, such as it is a separate product and is a registered trademark of Filemaker.
For legal advise you should seek a lawyer.