Silly question: if bonvolu means please, what does malvolu mean?
Perhaps you're right. This is the second time in not very long that I said that a word found in PIV is nonsense. Checking out the newly expanded Tekstaro, there are 21 hits for malvoli used as a verb - 13 of them in a single work by a single author. This is compared to thousands of hits for voli and ne voli.
That's probably as close to nonsense as we'll find in PIV - a mal-word used six times compared to several thousands for the non-mal counterpart.
I've looked up two of the six instances of "malvoli" and the expression in English is a little strange:
- mi malvolis partopreni = I hung back
- ne malvolu puni knabon = don't withhold discipline from a child.
So, I concede that "nonsense" is indeed a bit strong... but only a bit. :-)
Well, nonsense is probably a strong word. I think there are cases where you could use that. Something like, "Vi malvolas tion, ĉu ne?" I can imagine a mobster type scene, and it would be equivalent to this sentence following a dire threat, "And we wouldn't want that, now would we?"