@Silwith @WEISS
(
tl;dr version: The manga is mislabeled, if I associated the Japanese correctly, and should read "middle-aged man" instead of "old man")
Well, the word used is "ossan", which could potentially translate as "aged man" or "older man", since it can be associated with either of "old man" or "middle-aged man" (though it most typically associates with, and is translated into the latter). This differs from "jiisan", which
does directly translates to "old man", and bases its origins off of the Japanese word for "grandfather". Thus, it is directly equatable not only to "old man" over here, but also to English's use of "grandpa" to respectfully refer to old men one is unrelated to.
Similarly, ossan is often used towards middle-aged men in Japan the same way "old man" is used towards middle-aged men over here. Of course, over here that's typically a term of endearment offered up by the individual's own children or spouse, while in Japan it seems to be more popular in being used by strangers to indicate a casual or disrespectful stance towards a middle-aged man. That is to say, it's primarily a term used to refer to middle-aged men [albeit, often in a japing way which teases their age], or to encapsulate middle-aged and old men as a whole (
ex).
Point being, it doesn't actually seem that it would properly translate to "old man" for this particular manga (or in most circumstances, at that), which explains why the servant is still fairly fresh. This mistranslation of sorts is also likely very true of any other manga you're considering, wherein a male protagonist is younger than you'd expect of "old man", as ossan most naturally translates to "middle-aged man" rather than to "old man" (and yet, is often translated as old man instead).
Consider the appearance of the 63 [technically 73] year old protagonist of the jiisan titled
Jiisama ga iku (Translated: An Old Man in Counterworld) as it compares against the appearance of the 38-year old protagonist of the ossan-titled
Toaru Ossan no VRMMO Katsudouki (Translated: A Certain Middle-Aged Man's VRMMO Activity Log). The latter shouldn't have its title translated to have "old man" in it anymore than this manga should, unless we're considering a rather low threshold for the label.
In any case, properly speaking, this manga would be better suited to be titled "A middle-aged man forced to take a holiday" than "an old man forced to take a holiday".