Thank you for this post!! For those like me, who are simply making a retro-style game where they want EVERYTHING scaled to be pixelated, the simple quick answer is start your code with:

 from pyglet.gl import *
 glEnable(GL_TEXTURE_2D)
 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST)

And then all your usage of sprites, etc. from there on out stay nice and pixellated. No blurring!