Tim Kring Reveals why Peter didn't just fly and bomb himself - Heroes

You’ve been wondering, we’ve been wondering, and you
have to figure that Niki, Claire, HRG/Noah, Matt, et al, were
wondering, too. At the conclusion of the Kirby Plaza skirmish on
Heroes’ first-season finale, why didn’t Peter just fly his explosive
self up, up and away, instead of making Nathan take one for the team,
as well? Presented by TV Guide with that burning question, series
creator Tim Kring pauses before saying, “You know, theoretically you’re
not supposed to be thinking about that.”

When assured that viewers are, Kring confirms that — as many have
theorized — radioactive Peter’s other powers were “incapacitated” at
that pivotal moment, and “somewhere in there is the explanation” for
having Nathan grab his bro and do the “flying man!” thing. “But the
real explanation is that we wanted Nathan to show up and [save the
day]!”

“Yes, I will admit that there’s a very tiny window of logic there,”
Kring continues with a laugh. “But what can I say? It’s requires the
proverbial suspension of disbelief.” Which, when airing opposite 24, a
season finale is certainly allowed. — Matt Webb Mitovich, with additional reporting by Michael Logan

Link: Heroes Revealed

Personally, a bit lame of an excuse really. But what can you do? The show still manages to impress.