Does U2's lawyer do only pro-Bono work?

Technically yes.

Whether or not he collects a paycheck is besides the point. Although, if a situation were to arise where the members of the band had some sort of internal conflict, this might not necessarily hold true.

For example, let's say Mr. The Edge decided that he wanted a larger percentage of tour gross, leading to a rift between the band members and a falling out between himself and Bono. If he were to then sue the lead singer of his former group, and if the band's lawyer saw it in his best interest to side with Mr. The Edge, than the possibility would arise that the formerly pro-Bono lawyer would now be a decidedly anti-Bono lawyer.

An even more interesting possiblity would occur if the lawyer in question was so moved by the plight and situation of Mr. The Edge, that he found it in his heart to take on his cause free of charge.

He would then become, in effect, a lawyer who is both anti-Bono and pro-bono on the very same case. Whether or not the local Bar Association would find this to be permissible is another matter.

Man, they play "Vertigo" way too much.