i was thinking that maybe where simplzero is, time is in a cycle, as he stopped there to rest, he is also the one already there, waiting. the simplyzero that has come along is tired, the one already there rested, staying to rest and continue the cycle of asking the question "you should ask yourself who you are". the time that has been spent by the simplyzero waiting there might have been spent working out indeed who he is, why he's truly doing what he's doing etc. and indeed what he should do next.
if this as my theory is correct, then shortly after whatever is said, is said, then the rested simplyzero should go off in the boat calmly onto another journey which the tired simplyzero will travel down when the time cycles round again.
as to what he does actually say, perhaps something along the lines of ''am i you?'' though i'm worse at thinking of questions than i am thinking up scenario's
hopefully that makes sense to players