Less tossing him after his usefulness and more stopping something tragic from happening. IF they are going up against stronger and stronger foes and he isn't keeping up then it is only a matter of time before something really tragic happens. Sometimes you have to make the hard call for a friend...
VINT64
You forget that he only cared about the statues because he wanted to leave something behind for Frieren so that it wasn't just a passing moment in her endless life. That there was proof it happened and that they existed.
vodkavodka
I am going to assume Hemmel looks like that because he is now in his 80's. Most likely made his venture is his thirties well he was in his prime physically. A peek hero would be later twenties, early thirties. A mixture of age, training, and natural peek maturity to produce someone...