No. There's actually no compelling reason to have a baal t'filah
at all, if fewer than
a minyan have given up waiting and just decided to go ahead and
daven. But if ...
early in the morning, for example ... you think a minyan is
likely to arrive, and a
baal t'filah began the brochos, if there's still no minyan when
he reaches a
kaddish, the mourners don't say it, and in any case when a
kaddish is reached
without a minyan, it's not said.