I'm not ready to exit or even fade yet as it would cause too many family problems. One elderly relative seems to have dementia and the upset could prove fatal, so I will wait until the natural course of events happens (that sounds heartless - I am just being vague to protect my identity. I will be devastated when it happens)
Sometimes people need a push in the right direction. Your family member has dementia, and if you are correct about about the exit or fade, then there is still a bunch of steps in-between. Your family member will not really even notice if you were not the Watchtower Conductor. Stick to your guns- don't take that assignment. That was the best advice.
As far as being able to help others with subtle comments, it won't work. The comments would have to be pretty bold to even be noticed. I would forget this. The worst that happens if they insist you should do the Watchtower and you insist you don't is that they suggest you step aside or remove you as an elder. That would be lovely. I would step aside in a heartbeat using that excuse. Tell your relative (and others) that you are now free to spend more energy helping and being with your loved one rather than doing talks and preparing for every Sunday Watchtower study. That's way better than subtleness.
And I bet you don't get removed as an elder. So where I would step aside, you could probably keep serving. But you gotta move even the tiniest step toward freedom instead of taking a backstep.