Thread Expiration & Moderation of thread clutter

I noticed tinkering with threads, the expiration date of the thread only activates at the set time IF everyone has stopped talking in it.

If people keep talking in the thread, the timer raises. If i send a message at 3:57PM and the thread is set to expire in 1 hour, the expiration time would be 4:57PM, but if i send another message at 4:09PM, the expiration time of the thread extends to 5:09PM resetting the timer based on the most recent message.

While this is neat, what i want is:
Please make a way to set a hard cut-off expiration of a thread that doesn't keep extending, regardless if people are still active in the thread. Please also make a permission to enable or disable the extending-timer thread. 

Adding both i feel would make moderation easier, and would also be great for events too, as having a hard cut off where that thread ends, helps it not go on endlessly as long as people are active in it causing indefinite threads that should have closed. This can cut down on clutter of threads, as well as be useful for timed events. 

TL;DR 
Make a hard cut off option for threads in their expiration time where the timer doesn't grow based on activity, but cuts off at the set time regardless of activity, and add the ability to disable the growing timer threads. Doing both I feel would be great for moderation, cuttings down clutter, events, and much more.