It is a valid tactic.
For cheap, yet immensely satisfying kills:
Bombing a runway with the rinky-dink bombs in a G4M1 Betty bagged me a Rainbow XVI and a good laugh.
Sure beats bombing town centers or flattening hangars. And you are not preventing someone from upping like conventional vulching.
A ton of luck is involved of course, as the uppers you kill don't even spawn in until after your bombs are falling.