he probably would spare them, but either way this is a versus scenario which , as stated in OP is only relevant to the Destiny universe, we can assume is only limited to what we see in game/grimoire since its the only canon we have to go off of. going from this there is nothing the Destiny universe (as currently defined/limited) could throw at Goku that would be capable of defeating him, since the guy is practically a god who could destroy a planet and instant transmission as well as sense the location of his enemies through ki. so I will concede him destroying our entire known universe could be a stretch, but so far as the Destiny universe? theres only a handful of planets/moon and all the enemies are right there except the vex due to time travelly stuff and the Hive who have different dimensions/realms but even then its capable of going to those places and destroying them, as we have in game.