Fetishes are … kinda weird, aren't they? Very frequently, fetishes are illogical, and even, on the surface, fairly repulsive.
A very common example of this is the non-consensual sex fetish. Everyone reading/participating in this thread would likely agree that the idea of actual non-consensual sex (rape) is abhorrent, at the highest level. But ask yourselves, how many of you fantasize about this - either as the recipient … or the initiator?! Medfet is even in that category - I suspect nearly all of you with a medical fetish would be met with repulsion and disgust (and probably swift removal) if you told your primary care physician that you found exams and procedures sexually exciting.
I think, perhaps, that it is possible to both have this fetish (to be clear, I do not), and still have an intense respect for disabled individuals, and the challenges (many unnecessary) they face in largely an ableist world; just as the illogical attraction to non-consensual sex doesn't imply an actual approval of non-consensual sex. There are a great many theories about how fetishes appear, and certainly no good concrete understanding (It's not, say, the most acceptable research topic … “yeah professor, I know you wanted to study depression in adults, and I know we need some research grants, and I want to eventually make tenure … but I want to study kinky fuckery”) - yet the thing that is basically universally agreed is that paraphilia and fetish generally originate in a very different part of the brain than more logical thought processes (like empathetic feeling, etc) - and these two parts of the brain don't talk to each other very well.
I think the key to fetish is kinda in the individual response to it. Again - take the non-consensual fetish. Enacting a ‘non-consent’ scene, with fully consenting partners, in a reasonably safe and sane way is generally ok. There are even (bad) mainstream movies legitimizing this concept. Raping that gal you met at a bar cause she's hot and maybe she likes getting tied up and jackhammered like that video you watched on hampstersite last week is disgusting, repulsive, wrong, and illegal. Don't do that. Similarly, desiring those (or perhaps even a specific one) with non-normative bodies and experiences, and acting on those desires in a mutually-fulfilling, consensual, reasonably safe and sane way is probably ok. As @duckbillN95 points out, disabled individuals are not by nature asexual, and deserve to be loved and desired as much as non-disabled individuals. But objectifying those individuals, or their disability, for one-sided sexual gratification … isn't acceptable, as is the case with any fetish...
Going back to medfet, most of us would look at ourselves and say “Ok, I can separate my fetish and realize that it's inappropriate to objectify this doc at this appointment” - and not really feel sexual gratification when getting a yearly physical. Most of us would similarly agree that abusing that, allowing oneself to inappropriately take that gratification and mistreat the provider - for example, by asking for unnecessary procedures or unconventional things (rectal temps, etc) is not appropriate. I think this fetish is probably pretty similar. The ability to separate a specific attraction and still treat everyone with dignity, respect, and decency is what separates us from animals. I would suggest, then, that it is actions and behavior, not specific desires, that are wrong or right. The lack of that control, or realization of what the fetish actually is, and thus, why that control is necessary, like with any other fetish - is problematic.
As to whether it's medfet?
I suppose that would come down to the individual with the fetish itself. I'd suspect some would categorize it as such, and others would disagree. It likely depends on the root of the attraction. As one who does not have this particular fetish, I can't really comment on it; I'd not at all be surprised, however, to hear some connection to it by those who do.