Merr, methinks you're taking it far too literally...funnily enough though she said 'those who eat alone DIE ALONE', death is the last thing on her mind. It's supposed to trigger the response 'oh, I'll sit with you tomorrow then', or something along those lines.
It's unfortunate, but in situations like this you cannot take the literal or dictionary definition of anything an NT is saying
It results in you assuming they meant to hurt you when they were trying to be friends - unfortunately not realising that with this particular guy, that's not the best way of doing it
But you know what they say.
Easier to beg forgiveness than ask permission.
Eternal loneliness seems to the average joe to be worse than having to apologise for introducing themselves in a way deemed rude
I think it's kinda funny that she said such a morbid thing when he was tryng to eat lol.