I'm not 100% I followed your argument in the article, but I don't see how backing debt (or anything) with BTC weakens it.
What happens when you back debt with a hard asset like BTC is that you may not have enough of it to cover the amount you want to borrow in the conditions you want to borrow it.
But by definition if you're backing your debt "with" BTC, you either pay it back, or you lose your BTC, and then you have less BTC, so you can't borrow as much.
Yes, you can pay back in fiat, and that's why you have to overcollateralize your debt (say twice as much BTC as fiat you borrow) and pay an interest on top, otherwise no one will buy it.
Sure too, as a government, you "can" default, but good luck finding lenders ever again then, as Argentina learnt the hard way in the past, as is still suffering even today.
And if you force the central bank to buy that debt, like Argentina did, all you're doing is, as you said, monetize it and dilute the currency -- which leads to devaluation and price (hyper)inflation. So you can do that only for so long as well.
But I don't see why this would be different with BTC or how it could weaken it.