Note: I've not looked into the details of what square is doing. This comment is on AGPL in general compared to other licenses.

It does make some sense to see AGPL singled out, because it is different from most other free and open source licenses in one major way.

Almost all other free and open source licenses only require you to distribute modified source code of a derivative work you've made if you distribute that derivative work.

If I take code under those licenses, modify it, link it with my own code, and just run the resulting derivative work on my computer, they do not require me to distribute those modifications or my code, no matter what I'm using the program for, or where from, who from, or how I get its input, or what I do with, where I send, or who I give its output.

Not so with AGPL. With AGPL, the requirement to distribute derivative works can be triggered by code running entirely on my computer if it gets its input from and sends its output to people over a network.

That's a huge difference from prior free and open source licenses.