That's not how I see it. I'd correct this to "When the user performs a global search for a string using the Ubuntu desktop, Ubuntu sends that string to one of Canonical's servers to perform that search".
If a user wants to search his own local files without searching the entire Internet, then perhaps he shouldn't perform a global search.
The global search box (the Dash) didn't previously exist before Canonical invented it. I think it's fair that they get to define what it does. If you don't like it, then don't use it, or change its behaviour (it is open source, and you don't need a fork to change what is effectively a setting), or just use Xubuntu, Lubuntu or Kubuntu, all of which are acknowledged as official flavors by Canonical and none of which use Unity or the Dash by default.
"People will certainly make a modified version of Ubuntu without this surveillance."
And Canonical even support the existence of these modified versions! If you don't like it, just vote with your feet and install Xubuntu instead. Install popularity-contest to show people your vote. Job done.
By all means go ahead and complain that the default doesn't do what you want it to do, but please stop with the hyperbole that is actually misleading to readers about what the real situation is.