Radiant heat is great for intermittent heating. Instead of heating a space, you heat the objects (and people) in the space, and that heat can be felt seconds after starting the heater. It doesn’t matter if the air temp is actually 2C if the radiant heat makes it feel like 22C.

No, their response did not validate that. In fact, they said the words “it’s not technically illegal”. There is a possibly illegal way to go about it, and a legal way, and no way to prove the difference, but that doesn’t equal technically illegal.

I didn’t feel you deserved the downvotes for your first question, provided it was in good faith. You’re right, like all common misconceptions, it’s best to present clear data wherever we can.