I don't know why you say neither group understands each other when I literally said in my comment that my approach is probabillistic.
Also, how is configuring an infinite timeout (and checking whether the client is actually gone before manually breaking the lock lease) not an absolute guarantee?
Okay but then I really don't know what point you're trying to make. Either an infinite timeout, or non-absolute mutual exclusion guarantee: we have to pick either one. The right choice depends on the workload. There is no perfect solution that lets you have your cake and eat it too.
Also, how is configuring an infinite timeout (and checking whether the client is actually gone before manually breaking the lock lease) not an absolute guarantee?