Will Blue dot stingray eat Snowflake clowns?

They are RIDICULOUSLY hard to take care of.

While he most likely wouldn't eat your fish, he would eat any invert in the tank.

Stingrays need an insane amount of room. Liveaquaria lists them at 300g and I think even that isn't enough space. They also need super fine sand and close to zero rock in the display. I'd skip it.
I would change "zero rock" to very strategically placed. In the wild they could have rock formations, but it would be eithe little mounds or tall towers and arches. The mounds usually are single rocks or piles of smaller rocks broken off of a formation. Think Utah-esque.

Erin, if you didn't note his signature, his tank is in fact a 300. :) In case you missed it.