Not sure I'd rank him in the spot as Schwarzenegger, Stalone, Willis and them. What's the most bad-assness Snipes has to his name (in the same as others, not playing a comic book character)? Passenger 57?
The villain in Demolition Man, Passenger 57, Rising Sun, US Marshals, Drop Zone, countless direct to DVD movies. He's certainly a step up from Jean-Claude Van Damme, who Sly also asked to be in The Expendables.
Anyway, why would you exclude Blade? You wouldn't exclude Conan from Arnie's CV, or Sin City from Bruce's?