Is this terrible play of a 8/b hand?

[Walter]

I was watching a 30/60 8/b game recently and saw the following hand. I was wondering whether the game is just played differently at the higher levels or these players were just bad.

W brings it in with a 5. Everyone folds to M, who completes the bet with a Q.

4th street: W has 7h5s, M has QdTd. M bets, W calls.
5th street: W has 8c7h5s, M has QdTd7s. M bets, W calls.

Can this 5th street call possibly be correct? Isn't the low hand in a raise-or-fold situation? Unless M has two pair or a straight-flush draw, M is in trouble with a raise.

6th street: W has 8c7h5s7c, M has QdTd7sAh
W checks and M takes a free card.

7th street: M now bets, W raises, and M calls.
W hit her gutshot straight on the river (I had seen her hole cards on 6th street and she did not have a completed hand). M had made AAQQ.

Is this bet ever correct by M? It seems that the better play is to check and call to possibly induce a bluff and to avoid getting raised.