Quoting Heeeeeey, Sexy lady. ;):" Could he maybe be frustrated? Could his boss maybe tell him something like? Seems to me like he wanted ... [snip!] ... he asked his boss and might had gotten pissed when his boss said no. Took it out on you. I'd sit him down and talk to him. "
This. Or maybe when his boss said he could, it was an annoyed "Fine, since you don't want to do your job, you can have it off" sort of thing? Maybe that made him embarrassed and upset and that's why he got mad at you?
Not excusing it OP, just trying to figure out WHY, that way you can figure out what to do.