Even here, at the point at death, potentially for both of them, manhood is still of the utmost importance. Is there something about dying like a man? I mean, yes, of course there is. It’s how they get young men, through the ages, to risk their lives in war. The appeal of dying like a man is so strong that even thoughtful wise ones will join up to do it.
So here is Horatio attempting to die like a man, specifically a Roman one from ancient times and here is Hamlet attempting to prevent Horatio’s dying by invoking his manhood. He is basically countering one concept of manliness by pulling in another.
My god, the suffering men have put themselves through just to feel part of their own gender.