Mexico is somewhat variable as to what they allow or do not allow. Probably you will lose any argument where you come into dispute with them regardless of the facts.

The official regulations for Mexico can be found here though.
http://tijuana.aeropuertosgap.com.mx...en_objects.pdf

All pointy scissors are on the list along with pictures of cuticle scissors.

Not that I would expect it to be absolutely strictly adhered to all the time, every place in Mexico. On "not to the US" flights they let you keep your bottled water and you don't need safety baggies.