I believe that would be referred to as the "underside of snap" or something similar. Referring to it as "bottom snap" implies there are multiple snaps, which isn't accurate. I think this is just inaccurate information/typo
I agree that would have been better language. But let me add that the average age of officers at Moscow PD is quite young. All that's needed for employment as LE is a high school diploma in most places, for city police especially. Sometimes, they want a certificate (18 units) of community college or state university, sometimes they want an AA (rare, but if required, then in criminal justice).
I teach a lab class that counts toward the 18 units of some cities here in my region. It is popular with recent high school grads seeking to get a job (uniformed or non-uniformed) in LE, because having even a few units is better than no units. Another class I teach routinely is on the list as a lecture course (for LE as well as for other professions, like nursing).
One of the big reasons that LE management (with whom I consult about curriculum) wants these classes is to improve student observation and writing skills. I think this young officer did a good job and I've seen much, much worse in terms of LE-written affidavits. I've been given good examples and bad examples to work from. His is pretty good, he just has a few stylistic errors.
I think people are comparing his written efforts to those that are drawn up by actual attorneys or experienced paralegals.
I think you're right that it should have said "underside," but to him, it was "bottom of the snap" or "bottom snap." To me, the earnest and individual language of the PCA is supposed to show that an actual human, an LEO, went out to the seen and was tasked with later writing it up as a PCA - chosen due to his better writing skills, as he's definitely way better than average, IMO.
In some places, attorneys do assist LE in writing such things or at least review them, but that's not true in the smallish town where I live now, it's done entirely by police and their own admin staff. It's supposed to be in the "voice" of the officer writing it.