If you print tether it will only devalue tether and make the price of bitcoin (in tether) go up further.

Tether is a stablecoin. It’s not getting devalued unless/until there’s a run on it and it goes tits up altogether.

If you print it you either devalue the underlying dollar (and therefore tether), or you risk a run just as you would if you printed bitcoin.

You can't just print money without side effects.