Hi list,
It is more fair to consider OONI as an end-user network measurements tool running voluntarily and it should not be compared directly with various network measurements projects. Some relying on closed source software, non documented/hidden methodologies or could potential disclose user information to law enforcement.
There is nothing really illegal or improper (except ISP limitations/rules) that disallows a user to conduct network related measurements on it's own Internet connection. The user can decide the risks associated while running OONI, pretty much as in any other application for instance nmap and other security/port scanners.