No reason to combine the functions, just have an option to post both at once should you wish to do so. Lots of reason to post a NM only, say if you were revisiting a cache to drop off a TB or similar.
Also, no reason setting the NM flag within a Found log wouldn't still send the NM email to the CO.
Would be a minor feature addition to save a few moments while doing data entry is all, not suggesting replacing any other function, just an enhancement.