If you're long on an asset and are not lending it out, neither short selling nor leverage can hurt you with a fully backed stablecoin – you can always just go to its issuer and redeem it.
As an analogy, consider owning shares of some publicly traded corporation. No matter what happens on the stock market, this doesn't impact your ownership of the actual, physicaly corporation, which entitles you to dividend payments, a proportional share of its assets when liquidated etc.
If you're long on an asset and are not lending it out, neither short selling nor leverage can hurt you with a fully backed stablecoin – you can always just go to its issuer and redeem it.
As an analogy, consider owning shares of some publicly traded corporation. No matter what happens on the stock market, this doesn't impact your ownership of the actual, physicaly corporation, which entitles you to dividend payments, a proportional share of its assets when liquidated etc.