Yea but if you get incapacitated one of the first things they do to get to the wound is cut the clothes around the wound area. If you have pants make of knife proof material your life could be endangered.
Something thin and flexible won't protect against stabbing very well; the knife will just drive the material into the body. Cut resistant gloves are a thing and usually made of fine metal chain mail, but they're intended for protection from accidents using cutting tools, not assaults. The material used would probably not provide much protection against forceful stabbing.
If that worked, you could also sell to that company making the anti-rape pants.