But I guess that's like saying taking medicine is cheating, or using any assistive technology is cheating: there is one element that's different though in that you might be deceiving people into thinking you actually remembered their name.

Yeah, I think that assessment is correct, it's straight-up ableism (prejudice against using tools to do something as opposed to doing it "normally" with innate physical or mental abilities). Preference for "invisible" tools (say, a pill that improves memory) would be related. I'd even go so far as to say the characterization of the sort of remembering you do purely with your brain (as opposed to with a larger system that includes your brain) as "actual" remembering is similarly prejudiced. (Analogous to characterizing what Oscar Pistorius does as not "actual" running.)

I'd argue that whether or not someone is using hidden assistive technology is not anyone else's business. (And that they shouldn't be judged for using obvious assistive technology, either.) The exception is sports and similarly regulated competitions of skill and ability. It's not fair or right to treat everyday interaction as such a competition, however.