Throughout the book, Scourge shows little to no ability to deflect blaster bolts. Whenever he goes up against droids, he evades their attacks and responds with the Force and/or lightsaber strikes. Why? Because presumably, he was never trained to fight blaster-wielding opponents. Since his only opponents in the academy were other Sith acolytes, blaster deflection was probably not high on the curriculum. Sure, the instructors knew that he might occasionally have to go up against blaster wielders, but as the novel shows, unless you're a Badass Normal or you have numbers on your side, blaster deflection isn't something you need to worry about, as opposed to a Jedi, who a) primarily goes up against blaster-wielding opponents, and b) is trained to deal with solutions non-violently and non-fatally.
When Revan is trapped in a state between life and death, and fed upon by the Emperor? This is what Malak did to captive Jedi on the Star Forge in KOTOR 1. How else would Revan know what's going on, and be able to subtly resist and counter it?