Later in this issue (see previous S_D post) shows that this Starro guy is actually the consequence of a very young Starro core attacking an individual member of a psychically linked race. Short story shorter, dude dominates the mind of the young queen, but the experience prompts a shift from pacifism to "conquer everything" and an adoption of the name Starro.
So we already have an out in that he's an anomalous divergence from the normal Starro life-cycle.