No kidding? Lucaon is more than 50 years old.
No he didn't . What he meant by that is SERVANT should be PHYSICALY Strong not EASILY Bruised so that they can Do and Carry their Duties in the mansion .
Get it ? ٩(๑❛ᴗ❛๑)۶
The English translations are a little weird sometimes. In the original web comic it says something more like "Most servants don't bruise so easily" or "Servants don't usually bruise so easily", which could indicate that Lucaon has slept with other servants, but I think is intended to mean that Kyon is a little delicate/easily hurt for a strenuous job like being a servant.
So lucaon have done it with other servants as well? I thought kyon is the first.