Do you think Sans needs the weird route to happen somehow to get back to undertale? Cause if susie had been there she'd probably have stopped Kris and Noelle going in the water and the only reason she wasn't was cause Sans made her wait for ice cream. Also he gave Kris bread, so he could follow the breadcrumbs to wherever Kris and Noelle end up? To Gaster?...
the email voice does say "if we're lucky". seeing how harshly it condemns everything that happens at the lake through the other answers, it seems like it thinks what happens is inevitable but still wrong, which isn't really different from how sans acts in neutral runs. He won't even stop people killing papyrus, he just discourages it until the choice is made.
but he does talk to kris gently before they go to the lake, like he knows something bad is about to happen to them. and maybe those breadcrumbs will help both of them.
That would fit with my kinder idea, that Sans just knows its going to happen and that Susie wouldn't be able to stop it so he uses the ice cream delay to prevent her seeing it.
