This is why this specific definition is problematic: both "sideloading" and "install from Play store" are subsets of "installing".
If one limited the ability to "install from Play store", while keeping the ability to "sideload", would you say it's fair to say "installing is restricted"?
If one limited the ability to "install from Play store", while keeping the ability to "sideload", would you say it's fair to say "installing is restricted"?