The truth in POW is the longest chain of work, and since a majority is >50%, POW can withstand 50% byzantine failures...
...until hidden ASICs don't awake (or next-gen ones hit the market) and make last 2016 blocks orphaned.
This is exactly why its not Byzantine tolerant, as those hidden ASICs are the dishonest generals, and you only need 1 of them to undo each historic block. True Byzantine tolerant systems shouldn't have to undo history to provide the tolerance, otherwise there is no tolerance at all.
I'm not going to endlessly debate Byzantine agreement relating to Bitcoin. If you can't see why Bitcoin isn't by now, and don't believe that the model presented is secure due to your understanding, then fair enough, but I feel that we are going round and round in circles over the same argument.