Thanks for the additional information.  Changing the owner of the expenses to the person who has the more non-registered amounts helps. 

Thanks for clarifying what the optimizer's objective function is. I put the maximum withdrawal for the TFSA to zero and ended up with a slightly higher liquid legacy at death (not much higher, but higher). So I don't think the optimizer scenario is actually optimized exactly. Is it a heuristic search, or an exact search?  What's the search algorithm?

I'm trying to figure out why the optimizer would ever recommend spending down the TFSA if there's non-registered funds available.  The only thing I can think is to avoid triggering capital gains taxes.  Would there be any other reason?   Does the TIME MACHINE optimizer try to optmize taxes over lifetime, does it account fo taxes at death?  Most of my TIME MACHINE runs have the TFSA balance going to zero before death, which could reduce taxes during my lifetime (avoiding capital gains by spending tax-sheltered money) but leads to a big capital gains tax bill for the estate, that could be avoided.  

I've put the withdrawal priority to withdraw from the Non Registered accounts first, but when I run the optimizer it wants to withdraw from the TFSA instead of the Non Registered accounts, for many years.