I would guess (more or less) identically damaging multiple floppy disks in the same way would be easier with a laser than with something mechanical (e.g. a knife or a drill) (it is fairly easy to control power and duration of a burn), so it might well have been a laser.

On the other hand, disk tracks weren’t exactly tiny at that time in history.

I have almost no doubt that it could be a laser, it’s just unfortunate (and maybe a little bit suspicious) that I haven’t found it confirmed anyway. Almost like they wanted it to be a laser (hence the folklore around it), but had to use a less cool method to do it. But of course it might as well just have been a laser, and they for some reason declined to market or even just document it that way, for whatever reason.