Can you link the exact source? All I found on the website is this disclaimer, that claims complications around BitVM, not that it becomes unviable. Also, it’s absolutely normal to disable upgrade hooks for other soft forks while this one gets adopted. Not to mention any soft forks will require months or years of discussion and signalling before it has any chance of going live. It’s common engineering logic - don’t start building extensions around your house while its foundations are shaky.
I gave you my source. Also, I think you misunderstood how it works: it will prevent any consensus upgrade for the time it is active... And we all know how long emergency, temporary measures can last. Though in by view, "temporary" measures on something like Bitcoin make no sense start with. Either it's good and we keep it, either it's not and it never touches consensus. 🤔