Kenton says a few words in defence of Toby. Yes, he can be flaky and unreliable, but he’s not the waste of space David sees him as. David abruptly ends the conversation. He doesn’t need a character reference from Kenton, who isn’t much reliable himself.
Kenton does already know what his brother thinks of him. The best thing he could have done in support of Tobes is to shut up. Is he really that stupid? Or in love with the sound of his own voice?