Unless there’s new information, this is exactly what the Snowden leaks exposed.
Snowden wasn’t showing the world the NSA surveillance systems against them; he was trying to show that the US was illegally spying on its own citizens by leveraging the five-eyes countries to collect and aggregate the data on their behalf.
I was always baffled by this "revelation". Everyone has always known about the five-eyes arrangement. It was common knowledge when I was growing up in the 70s. It wasn't new info.
There were a lot of things Snowden revealed, but most assuredly it was also about spying on US citizens. The NSA directly wiretapping people, even in cases when all communication was domestic. The NSA working to bypass security via routers diverted during shipping to Google, Facebook, and others, backdoors installed, thus compromising their infrastructure.
Back to the 5eyes, there is a difference in terms of scope and scale, when it comes to a foreign country spying on your citizens, and you doing it. The scope is entirely different, the scale, the capability.
It does matter whether it is 5eyes doing it, or whether it is domestic.
Now, does this stance matter overall? I don't know. It's a nice moral stance, I think. Is it functionally realistic?
I just don't know.