It is not a semibluff
any hand that would not currently win at showdown but has the capacity to become the best hand and is played aggressively is a semi-bluff.
He is trying to max his EV. Maximising EV doesnt mean just trying to get all-in with any draw that you know has around 50%+ eQuity against your opponents entire broke range. It means playing the hand in the way that you max profit vs this particular player and his likely holding.
The potsized bet from matusow is either a bluff or a strong hand thats not folding. Given how far ahead of the bluffs PH is, I dont see why he should just opt to flip vs the strong range when he can play later streets with posn. As soon as you shove in this spot, you just give up your positional advantage and flip a coin.
Its no particular victory for PH to raise the flop and force out 8h9h...