I want to double down on the comment you're answering to. I believe that LN spanning two blockchains - Bitcoin and stablecoin - would be better than LN only on the Bitcoin chain but with two assets.
Imagine (God forbid) that Bitcoin forks an offshoot called Bitcoin Crash. If the stablecoins are issued on the main chain, the issuers now get to decide which fork to support. What if for some reason they choose Bitcoin Crash? Do we really want to give them such power?