The copyrighted work has been included in content that is monetised. The guy is making money and the musical work has some part to play in that.
Here’s a counter example.
Imagine if I recorded Bono from U2 chatting about random stuff between playing live tracks at a concert. But I inadvertently caught the last 10/20 seconds of most songs. I make these recordings publicly available and monetise them.
I was only doing it to catch Bono’s musings between tracks. But people can hear the copyrighted material as well.
Under copyright law, I have made a copy of the musical works (mechanical right) and have made them available for consumption (performance right).
Just because I only caught snippets doesn’t matter. It might affect the amount of money I need to pay rightsholders, but there is copyrighted material in those recordings. So the rightsholders should be remunerated.
That’s it. That’s the whole fundamental point.