Rabbi Zweig answered in this week's Insights:
"Aharon recognized that while it’s true
that redeeming Bnei Yisroel and
becoming their leader was a position
of greatness, it’s not an appointment.
In other words, when Hashem asks
you to take this role, it’s one primarily
of service to Bnei Yisroel and
Hashem's plan for the world. This job
isn't about the stature that comes
with the responsibility, it’s about
being a servant to that responsibility.
Moshe was bothered by the stature
associated with the job. He spends a
week explaining why he isn't the right
person for this job. When at the of the
week he still feels that Aharon would
be jealous of his new position,
Hashem gets angry and explains to
him that Aharon understands that this
is about responsibility to serve – not
the associated stature. It is for this
reason that Moshe loses the right to
be a Kohen and this role is given to
Aharon. Kohanim are “Meshorsei
Hamelech” – ministers of the king.
There is no sense of stature in this
leadership role; only responsibility to
serve Hashem. Aharon understood
that when called to the responsibility
of serving Hashem you have to accept
and that stature plays no role in the
You can read the full answer here.