This may be subject to feature request.
However, if you are ok with using polling of last boot time via WMI as reference for this check, you could be able to use custom swql alert to achieve what you are asking.
Consider custom SWQL alert over Node entity with condition similar to this:
WHERE ObjectSubType = 'WMI' AND Unmanaged = 0 AND MinuteDiff(LastSystemUpTimePollUtc, GETUTCDATE()) > 5
This should get triggered for all managed WMI nodes for which poll of last boot did not happen (or did not get processed) during last 5 minutes.
Will this work on a machine which had not been able to poll yet? I know I have some servers which were set up with WMI and since have stopped providing counters...will it detect these, if I had just now set it up?
Well, it won't. But you have complete freedom to extend condition further to cover even those cases:
WHERE ObjectSubType = 'WMI' AND Unmanaged = 0 AND (LastSystemUpTimePollUtc IS NULL OR MinuteDiff(LastSystemUpTimePollUtc, GETUTCDATE()) > 5)
Bump for they day crew...