Update Activity Owner to Account Owner when User Status changes to Inactive

I am trying to find a way to update Activity owners' records once the owner becomes an inactive user.

I was thinking about a workflow, but it appears there isn't anything to trigger the Activity just because the Owner's User Status has changed to inactive.

I tried:

Condition:

JoinFieldValue('<User>',[<OwnerId>],'<Status>') <> PRE('<Status>') AND [<Status>] = "Inactive"

Integration Event Action:

Activity

Activity Owner

Before Modified Record is Saved

JoinFieldValue('<Account>',[<AccountId>],[<Owner>])

The interface accepted the above code, but 1) it didn't work and 2) it caused other Activity workflows to fail.

I'm pretty sure this isn't possible, but does anyone else have a workflow solution to reassigning activities?