If Daystrom didn't believe the galaxy was mankind's to give or take, why would he support the sending of starships there, crewed or uncrewed? Surely the correct choice then would be to stay home and
to tell the machines to stay, too.
It seems likely that ol' Dickie gave a somewhat different sales pitch to those Starfleet representatives who approved the test program, including the final wargames...
Automated ships would be useful for an openly imperialistic or clinically paranoid culture, of course. But Starfleet had just had an encounter with an automated berserker machine some 500 stardate units prior to this episode. Were they really going to fight fire with fire, despite seeing how senseless the concept was?