Why does Akiba refuse to speak to Elisha when they see each other on the road?

Akiba refuses to speak to Elisha because he is honoring the orders of Elisha's ex-communication. Once good friends, the two men would like to say something to one another, but Akiba is bound by the laws of his faith. Elisha is understanding, Akiba doesn't wish ill fate upon Elisha, and he knows it.