Had shop install new spider injectors and engine blew at less than a quarter of a mile. The engine has 252,000 miles. Hole in piston. Is this a coinsidence?

 

Maybe they left something in the intake manifold.

 

I'll second something was left in the motor to blow a hole in a piston a quarter mile down the road after being worked on. Just enough time for a bolt, nut, etc. to work it's way into a cylinder to do the damage and without a full tear down and exhaust inspection to find something it's tough to prove.
I did the spider injectors in my old '99 Yukon at 100k miles and drove it to 190k miles and sold it running fine. New injectors will not hole a piston. Only a foreign object or extremely severe detonation will do that.