As per https://biomemakeover.laserknights.com/notes/mob/stone_golem/ stone golems are supposed to have crossbow.

The golem isn't attacking me, or enemies, spawns without a weapon and just sits there.

Turns out that you have to "give" them a crossbow, this should be reflected on the wiki.

This is intended behavior and is reflected on the wiki.

Yeah, it does already say this on the Wiki, though is probably easy to miss under the image.

Thanks for the report anyway!