FUTO changing the definition of open source to suit their business model is like that time US Congress decided that pizza was a vegetable because it has tomato sauce.
FUTO’s EULA may superficially resemble a true free software license (and may be good enough for you, personally) but it fundamentally undermines core tenets of the free software movement in order to preserve their business interests. All pseudo-FOSS licenses (whether of the “ethical” or the “business” variety) do this, because they prioritize the interests of the rightsholder above those of the community and the user. If important free software projects like Linux and Firefox were released under this license the free software world as we know it would not be possible.
As proprietary licenses go, it’s certainly far from the worst.
This is why the marketing around flatpak bothers me. It’s touted as some kind of “universal Linux package manager” but Linux is just a kernel - all the stuff that apps depend on comes with the distro. So, in order for flatpaks to be “distro independent” they basically have to supply all the stuff that normally comes from the distro - effectively building a second distro on top of your existing one.
Nix and Guix are the same but at least I think they’re more up front that they are effectively distros that can run on top of your existing distro or as a standalone operating system directly on top of Linux.