Not forgetting that TomTom were forced to pay damages for ignoring the GPL. They were certainly not the good guys in this kind of scenario.
He makes the mistake of assuming a complete erase each cycle of full disk. In reality, that sort of runaway process would fill the disk and then start erasing small parts to make room for more data. If 1K of space is made each time the disk if full then that actual cycle would be 1 x 64GB plus 2m x 1K.
/those/ figures in and it turns out the disk will be trash within 20 minutes