[Jason knows the older man is taunting him and it's pissing him off. The combination of someone with his face taunting him while he's beaten up, heavily bleeding, and feeling trapped is sending him into a rage spiral. It's mentally sending him back to a particular night when he was in a warehouse in a similar state.

And just like that night, he answers the taunts with a spit to his enemy's face. Additional slashes to his face be damned]