That makes a lot of sense to me. I may be remembering this incorrectly but I thought there was a WoP saying something like a shard blade could cut aluminum but it has to be thin enough that a normal sword could cut through it. Then Brandon specifically dodged or RAFO the question. Of course I could be completely making this up.
Edit: ok I’m completely making this up because I found a WoB that specifically says a shardblade can cut aluminum.
WAYNESPREN
Can Shardblades cut aluminum?"
BRANDON SANDERSON
"Well-um-yes, yes they can."
I also found one answering my question about tin foil hats!
QUESTION
Which I did catch was very entertaining to see like that [regarding the Aluminum Hats].
BRANDON SANDERSON
I built aluminum to do all sorts of funky things to all the powers, and I actually hadn’t made the connection of tinfoil hats until after I’d built it in, and I was writing it in Alloy of Law, years after I built it in, saying “Wait a minute! I just put tinfoil hats in the book!” (laughter) So I actually built that without thinking that there would be a joke to that.