I'm gonna tell my younger sister that she's real lucky I didn't exert my right to erase her memory.
In Klingon society, it has been established that the elder son speaks for the House. (Kurn said this in
"Sins of The Father", which was why he sought Worf to begin with.)
With what happened in "SONS OF MOGH", Worf essentially had power of attorney over Kurn. I know some people question Bashir going along with this, but two reasons stick in my mind why he did.
First, he already healed him from a suicide attempt by that point...
twice. Once from the ritual, later for letting himself get shot. A suicidal person that dead set on dying will find a way to get killed, sooner or later.
Second, Bashir respected Klingon culture and laws. He also never imposed his own views onto patients. (Actually, this is my reason for why he is my favorite of all the doctors. More than any of the others, except maybe for Phlox, he kept his own sense of morality out of patient treatments. This is precisely why Crusher ranks as my least favorite of the franchise... see TNG's
'Ethics".)
Given that Worf admitted he couldn't go through with the ritual again, it was really the only option left.
And honestly, the person who is really at fault for coming up with this idea is Dax. Worf simply took the option he was presented with.