Colloquially perhaps, but it is wrong from a technological perspective, and IMO that matters.

Sounds like a middle manager adding technical terms to sound more... technical.

Not really, since in the context of a store, "location" often refers to an instance rather than it's location coordinates.

A better analogy would be saying the store's address is closed. Doesn't make sense.

OK

The URL https://www.bl.uk/ is working fine, but the site is busted.

It returns a resource but I wouldn't say it's working.

I found it confusing - if a URL is "offline", I'd expect some kind of error message like connection refused or no such domain. The URL here is not "offline", it's the BL that's offline, and the BL isn't a URL.

If it displayed the Cloudflare 502 Bad Gateway error page, would you consider the URL to be offline?

There's no Cloudflare here, but I see it as conceptually the same thing.

Custom vs default error page