I could be mistaken, but perhaps Buttered Toast is referring to Legga's simultaneous requests for favors and inability to reciprocate.
A coward is a coward because, while they recognize the honor in acts of self sacrifice, they are unable to comply due to self preservation instincts. Buttered Toast is pointing out that Legga does not care about the honor in self sacrifice. Otherwise he would not be asking so many favors due to fear of facing requests for reciprocation.
This could be the case, but my theory is that Legga simply doesn't understand the consequences of his own actions. It's not that he lacks a sense of honor, he lacks a brain. He's only now realising the grave he's dug. And yes, he's a coward.
But that's just my two cents. Who knows what the case really is.