I think most people could see the potential usefulness of a “check if Assignee is out of office” condition in terms of writing rules about reassigning those tasks.
However, in this particular case, I am attempting to manage my neurodivergence by creating a “nag me” rule in MyTasks. I need something to keep bugging me about a particular, periodically recurring task until I finally address it. It’s important that I do this task if I’m available to do so, but not so important that someone else needs to add it to their plate if I’m out of office. In the interest of good programming and inbox hygiene, a simple check to see if I’m out of office or not could prevent the rule from firing off a bunch of unnecessary notifications. (The fact that I need this rule in the first place is a good indicator that I’m not going to remember to turn the rule off before I go on vacation. 
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Solving my particular request would also entail enabling “Assignee is” conditions in MyTasks, which I assume is not currently available because the assignee in MyTasks is, by default, me. Enabling “Assignee is” filters in My Task may also become useful as first level subtasks assigned to other people will now be visible in MyTasks per this product update announcement: See your subtasks directly in My Tasks grid✨ .