Interesting - I didn't know that. But the parent was pretty obviously making the association between forms of damage which definitely increase cancer risk (sunburn) and non-ionizing radiation - which does not. The type of burn he observed is thermal.

So even if thermal damage (or just damage in general) can increase cancer risk a little...it's not remotely the same thing as sunburn or gamma radiation, and as it pertains to cellphones completely irrelevant (because a cellphone is not a 40W antenna emitter).