Hating somebody for writing free software is not anywhere near reasonable. He never forced you to use it.
I don't think it matters if the software in question is open source or closed source, or if it was obtained for free or paid for, or how the developer was compensated, or if it were developed by an individual or an organization, or why lmm had to use it in the first place.
Causing people unnecessary grief will invoke a negative reaction. That's perfectly understandable, and quite reasonable.
That wasn't Lennart's fault. PulseAudio is a really mature and stable system now.