Our dealings with the Centauri prior to the Earth-Minbari War were
primarily economic and cultural, with some technological elements sold to
us as well. They have no interest in getting into a war, especiall on
behalf of someone else. They were primarily foot-draggers during the war,
selling some stuff to us as needed, but generally not doing anything the
Minbari would get annoyed by. In particular, they didn't sell us any
weaponry. It was, oddly enough, the Narns who sold us many of the weapons
technology we used in the war...stuff they'd captured from the Centauri
during their own revolution. The Narns needed the money, and need to
forge an alliance with the EA, however tentative.

jms