“Was their professional judgment impaired by their fetish?”

That concern is the correct one.

But: It doesn’t particularly matter how the fetish works, because people will assume that the existence of a fetish guarantees that judgment is compromised. That assumption will often be couched in terms of skepticism and doubt rather than as a flat statement of mistrust, especially here in the US. Unfortunately, the concern is valid, even when the frequent-but-not-always underlying assumption is not.

Has the licensing board ruled on whether or not patient abuse occurred yet?

If not, then, like, maybe don’t read this article at all. Wait for the outcomes of a professional evaluation. Don’t chase this particular ambulance. It’s not healthy to stop and admire a train wreck, and if it ends up not being a train wreck for patients, and professional care was given regardless, then it’s just gossiping about someone making irreversible physical edits to their body — a completely normal event around the world, starting at birth in many cultures, with widespread differences within each around how little/much editing is too little/much. I know HN likes to clamor about slipper slopes, and this is the sort of checkout aisle magazine headline fodder that leads to that:

Should someone who has had breast reduction surgery be permitted to perform them?

Should someone who has had leg lengthening surgery be permitted to perform them?

Should someone who has had a facelift be permitted to perform them?

Should someone who has had a tattoo be permitted to perform them?

Should someone who has had hair removal sessions be permitted to perform them?

Now, replace ‘to perform them’ with ‘to advise patients about them’; does the answer change?

Yes, amputation is ‘extreme’; so are many, many other voluntary (e.g. heart tattoos) and involuntary (e.g. dysphoria-treating surgeries) body edits. The level of concern expressed for the practitioner’s judgment should not be a function of the severity of edit, and we should always be alert for signs of corruption in those practitioners — whether it’s tattoos, leg lengthening, or limb amputation.