Not sure whether it's moot. Even though they're not legally required to provide cash, Tether's accomplishment of establishing and then maintaining a $1 market value is presumably assisted at least to some extent by their offer to provide it. To what extent precisely remains to be seen. The longstanding doubts about Tether's reserves didn't impair its market value; the more recent revelations may not either, but that's not certain yet (in particular, if the market is being manipulated, the muted short-term response may not last).

But yes, they are protected from runs.

Edit: Also, that text wasn't always there; in 2015 they claimed Tether was "redeemable for cash at any time" [1] and didn't have any similar disclaimer in their terms, as far as I can tell [2]. In addition, even with the disclaimer, if someone sued Tether for breach of contract (because they breached their promise to hold 1:1 reserves), fraud (because at certain points they made false claims that they did hold them), etc., they might be able to recover some USD in the form of restitution.

[1] https://web.archive.org/web/20150320090830/https://tether.to...

[2] https://web.archive.org/web/20150921163244/https://tether.to...