Disintegrating interior heater tube foam!

[Jerome damato]

Hi, I am new to the forum (stalker for ages) and really appreciate both the knowledge and sly humor of the place thanks for many a great read and insight-

I have a ‘66 912 resto I’m into the metal work on. Just replaced floor and am onto the rockers- noticing that the interior heater tubes which are metal on this example look to be in solid shape with just some surface rust which comes off with a scour pad.
The issue is that on reaching hand inside the tube I felt that there is a foam tube INSIDE the tube- and on one side it’s sort of deteriorating.
We blew some air through it and nothing comes out- however, my concern is that once the engine starts kicking out that good heat in the winter that a funky smell might arise (this car spent a lot of time dank/damping away in a Long Island barn. Like 50 years.
My metal guy is eager to seal it up and move on as he believes it’s a non-issue. Wondering if anyone has any familiarity with this.
These are not the cardboard variety tubes and I also just wanted to share a pic as I don’t know if the metal type is unusual and might be useful to see for someone else-
It’s an interesting design. I think like a muffler. Outer metal canister, presumably some layer of baffling or insulation, then inter metal liner, THEN the foam tube I mentioned! Must really be concerned about noise transferring from motor.
Thought I had a pic of the foam tube but I don’t- basically if you peer into the hole at your ankle where the heat comes out you can see the end of it in there - or just feel around with fingers.

That’s all I got- thanks again for all the great reads 🙏