[Tommy]

OK, here's the short answer: I'd move that line.

Here's the long answer: First, it appears things have been that way for a long time. If the previous owner didn't notice a problem, maybe its OK for normal use. I wouldn't trust it for a track day event where the exhaust gets much hotter and the brakes are more critical and used harder.

Heat can be transferred in several ways. Radiant heat is transferred by radiation and is what you feel when you stand a few feet from a hot fire to warm your hands. Convection and conduction are when the hot object warms things around it (e.g., air and metal that touch it) and those things convey that heat to things they touch. A simple sheet of foil can block radiant heat. But that line is surrounded by things that will absorb heat from the header and then conduct heat to it. An insulated sleeve is mostly for blocking radiant heat and won't block much conducted heat. That is why I would move the line if it were my car.