It is not a bonus action to draw or sheathe a weapon. Basically you get four actions according to the books (action, bonus action, reaction, move) and then they backtrack and give you a single free "interaction with an object" on your turn, as part of an action or move. If you need to draw two weapons, you get one free and need to spend your action doing the second unless you have the dual wielder feat. Basically everyone has quick draw now. The real thing I think Iaido should do is let you draw and attack as a reaction, plus some initiative shenanigans or extra damage.