Hmmm, HAL didn't hit the blank... Why? Does that mean that HAL didn't have any blanks? Not necessarily... Notice that if HAL has one blank other than the 6-0 and hits it, then he should know for sure that they would play the 6-0 and keep the head of the blanks, which would very likely be a ticket to win the round.
On the other hand, HAL is
repeating the 1, so maybe he is convinced that Adam won't be able to deal
with another 1 (which BTW, leaves a head on the 1's), and force Adam to
hit his own blank... In fact, notice that since Mike doesn't have
any 6's, and there is one on the table, and you have two (and Adam has
two tiles), that means that HAL must have at least two 6's. That
means that he played that 6-1 because he chose to, not because he had no
other option.