The option role includes aria-checked in supported states and properties, which inherits into treeitem.

Since aria-selected exists on both and already indicates selected state, it's unclear what additional meaning aria-checked could convey. E.g. is there a use case for either of these currently valid option states?:

<div role="option" aria-selected="true" aria-checked="false">Selected, but not checked</div>
<div role="option" aria-selected="false" aria-checked="true">Unselected, but checked</div>

If not, I believe it should be removed from option (and treeitem). I've already run across the above markup (odd as it seems) in a product. It resulted from some confusion reading the ARIA spec and thinking aria-selected indicated current focus and aria-checked indicated selection, so updating to a more strict set of allowed attributes seems beneficial.