Why does a floating license need to be node-locked? isn't it supposed to be not limited to a specific computer?
The purpose is that the license for the actual program (your performance profiler) is not limited to a specific computer. Limiting the license server to a specific computer doesn't affect that.
That is actually how it is handled in FlexLM. You get one "master" license file that only works a certain computer which is running the FlexLM server and which includes the maximum number of running instances (overall) for your program. Now when other computers start the program they contact the license server and if a slot is free the program will start.