I've met or have known my fair share of instructors were could probably be considered well informed. The majority of them were LE instructors, but now and again I came across some who also taught outside/commercial classes.
While it might have sometimes been of occasional passing interest what some instructor might be carrying, it wasn't of any real significance or interest to me. Instead, I was primarily interested in
how well they could use whatever it was they were carrying. That hasn't changed.
Over the years of seeing different age groups (generations, if you'd rather) come through ranges and classes, I noted that the choices were often influenced by the backgrounds and work experience of the instructors.
The "age of plastic" could still mean someone who may have formerly used 1911's or revolvers for work, of course, depending on their age and experience, but it often started to mean that they were simply new enough to being instructors that they'd only really experienced using one or another of the current crop of plastic pistols.
I've seen my fair share of newer LE firearms instructors who simply weren't at all familiar with 1911's or revolvers. The lingering presence of some TDA (DA/SA) pistols in the LE field was as close as some of them had ever come to SA or DA triggers, and not everyone was comfortable or seemingly well experienced in those.
I've had some less experienced firearms instructors look at me weirdly when I opined that there's a difference between being experienced "enough" (with a particular gun make/model/caliber) for the specific agency or student/staff group you're responsible to help ... versus being a firearms instructor well versed and experienced in using a variety of handguns that might be used in both duty and off-duty roles by the people you're helping train and qualify. (Kind of like so many newer LE instructors want to be rifle instructors, but give scant attention to learning to run/teach shotgun.)
This is where I suspect (hope?) that private/commercial firearms instructors might still have some more leeway (or at least interest) in what they're willing to learn themselves, and make themselves able to teach to others.
Equipment choice is either a personal matter (for any number of possible reasons), or a professional matter (issued equipment, policy restrictions, etc). If someone is looking to an instructor for guidance or suggestions, hopefully that person understands the reasoning being used by the instructor, and can decide for themselves whatever has influenced the instructor is of any particular significance or relevance to them, as students. I've certainly helped other shooters (as an instructor) when they were using different equipment/weapons than me, and if it worked for them, it worked for me.
Whenever I've been asked for advice in selection of off-duty weapons, I always tried to take the familiarity, training and experience of the person into consideration. I listened to their preferences, and asked questions to try and gain some insight into why they had those preferences. I also tried to let them try examples of their preferences on the firing line (if I or another instructor owned them, or we had any in the training inventory).
Naturally, sometimes a little live-fire can change someone's mind, and then it was a matter of finding out
why they suddenly changed their minds, and going forward from there.
It probably helped that I owned/carried 3 of the major pistol duty calibers, including a variety of pistols in standard, compact & subcompact sizes, and still used/carried revolvers and 1911's.
I didn't shill guns or calibers, nor expected anyone I was responsible to train to emulate my choices or preferences. My choices, and reasons, might have little relevance to any particular guy or gal asking for suggestions. It
had to be about, and
for, them.
