I agree I would never put a sealer (permatex) on a head, but the copper spray is more of a tack / glue, kinda like Indian head shellac with a smooth coating.
If for some reason you go and remove the heads after using the copper spary (upgrade, whatever) you will find that the head gasket will actually rip in 1/2 with part of it bonded to the head and the rest to the block.
Everything is debatable, but I also have alot of grey hair and have been putting mopers together for over 30 years.