You no that is different from what you were referring to as oiling a trigger, but I bet you wont admit it. If you allow actual oil in your trigger group, you will experience issues with gumming and grime long before you would have had issues from rust.
There won't be any issues with "gumming and grime" if you
clean it often before reoiling
If RUST is the problem, oil is the solution
It doesn't have to be dirty 90 wt gear oil to do the job
The first ingredient in lighter fluid is an "oil":
Light Hydrotreated Distillate