I'd be thinking more about what my boss would do to me when I came back to work, not myself! For this reason, I've stopped kicking roosters, even if it's just a nudge. I only resorted to this in the past when my younger brother was getting attacked, or I was in front of a guest or family member. But the last few months, thanks to BYC, I've seen how lucky I am that I have not caused serious damage, so I've handled these problems in other, more HUMANE ways.
That's horrible! I would have more remorse for the animal! Roosters could be much worse than that if they wanted to. Sounds like typical mean roo behavior to me. Unless the owner gave you permission to kick his or her's animals, the risk really shouldn't have been taken. Now a life has been wasted because the behavior wasn't given the chanced to be managed in other ways.
I've had scratches from roosters, bruises, and scars that will be there for life. Sometimes this is what we must pay to make certain we don't kill anything. I'd rather have injuries and physical wounds and proudly say that I'm tolerating the rooster, or even got rid of it, rather than live with the burden of guilt that I had killed an animal who didn't even belong to me.
If you can't deal with aggressive roosters, bring the issue to the owners' attention.
That's all I have to say.