The problem with your presentation is that his account never goes down to $55,000. It continues to be $90,000 BUT he has an outstanding loan of $35,000. The loan is an asset of the plan (or his account), so his vested balance hasn't changed.
The second loan will be based on his account balance, which as noted, it the $90k number. Of course, in calculating how much is available, the outstanding loan balance (actually, highest outstanding balance in the prior 12 months, which in this case would be the full $35k) need to be taken into account in applying the maximum loan value.