https://imgur.com/rgU8uZx

This probably isn't intended behavior, but I don't think it should be removed completely. It'd be nice to be able to side load just the far lane (left side in the image) like undergrounds.

This is vanilla loader behaviour. Modders have almost no control over transport line mechanics that won't tank UPS.

I don't know enough to say why or why not, but Krastorio's loaders do not allow side loading, and if I understand correctly they are also vanilla loaders. Just as a FYI, obviously if you don't care to fix it, it's not a problem, just thought I'd mention it.

pretty sure that k2 loaders are actually stack inserters in disguise.

they're not. The miniloaders mod is inserters.

Thats why it can unload from trains and Deadlock's loaders, and the K2 loaders cannot. Because they are just the vanilla entities from the game.