*** Speculation! ***
Something else - why did Hiro appear?
At that moment, Mohinda had been doubting everything, and a reason to convince him to continue his father's work seemed required.
Then time stopped for the young doctor and Hiro appeared.
My presumption was that Hiro needed to pass on a message to Mohinda. But why not appear to Mohinda directly?
Maybe he couldn't. In which case, why then the young doctor?
And the young doctor can only fly when near his brother.
So the suggestion is, the young doctor's ability isn't flying - but instead the ability to absorb and use superpowers near him.
That's why he can fly near his brother - and that's why he alone would be able to see Hiro through time - absorbing Hiro's power.
Evidence of picking up before hand?
Well, the young doctor was exposed to Isaac the artist, not least when Isaac had overdosed. Isaac dreams the future. The young doctor was dreaming of flying, not least from when stood on the end of the building when his brother helped save him.
Which suggests he absorbed the precognition ability then, and that he's able to absorb superpowers in general - at least, the one's we've seen.
Which suggests he could be the most powerful in a sense, if all are joined together with him - as wouldn't this suggest he could absorb everyone's powers?
2c.
