The subject at hand is related to this question in particular: https://physics.stackexchange.com/questions/131619/how-does-ohms-law-apply-to-superconductors
If technologies are only on-topic if they are commonly used, then I suppose all of the technologies used in amateur radio today would have been off-topic in the years leading up to their becoming widely practical. Amateur radio has always been about experimenting and innovating with new technologies. Superconductor technology is getting ever closer to becoming practical for use in Amateur Radio.
Also, the question had as much to do with the application of Ohm's Law and Joule's Law as it did to superconductors. Both of those concepts have been sources of license exam questions since before the 1970's when I took my first exam.
The question relates to principles fundamental to current, resistance, inductance, and magnetic fields. All of them fundamentals of radio.
Yes, the question relates to physics, the branch of science concerned with the properties of matter and energy and the relationships between them. But any subject that deals with natural phenomena, from radio to meteorology to astronomy, will resort to the use of physics to gain an understanding of the principles governing those fields.
I can't imagine how anyone would find the migrated question as off topic for the HR SE.