Ask away! 
Your question is really a general question about how the latest version of Rule Machine works, and as such, this thread may provide more information on what you're looking for:
Specifically, some examples early on show motion lighting automations with cancelable delays (you can ignore the equivalent rules in older versions--part of this guide is intended to help people upgrade). It's a totally different result but the same ultimate rule format.
But to summarize, here's how it works: your rule actions run any time an event fires that matches any trigger. Your trigger here is "lock *changed*," which means "lock locked" or "lock unlocked" (the only two possible states). Let's say the lock becomes unlocked. The IF... will evaluate to to true, so the delayed action will get scheduled. If nothing else happens, RM will follow through with that schedule and run the following action (locking the lock) at that time. If you lock the rule in the meantime, that matches the trigger, so the actions will again run. This time the IF... will evaluate to false, so the ELSE will match and run. What happens here is that the delayed action (technically the delay and everything after it, including locking the lock) gets cancelled. So, yes, they are in mutually exclusive blocks, but that's what you want to get this behavior--and it works because of your triggers. (A common mistake is people making rules like trigger on "motion active" instead of "motion changes" with an IF/ELSE similar to the above; one half of that rule will indeed never run.)
