If you use any acrylic that is suitable to hold water then you can rest assured that it will be fine. Acrylic does not shatter when struck like glass does.
Through several experiences, and several witnesses, this would not be the case.
Acrylic bends, making it tough to crack, but hard acrylic such as crittle containers, or acrylic betta kits, will break from something as smalll as a neogonodactylus. In this case glass would be the 100% safer option. Back in the day I made a refugium out of an acrylic betta container, and it lasted a week before cracks were made, I soon realized it's as sturdy as a critter container and tore the whole thing down.
However a "shatter proof" acrylic setup such as what seaclear 30 gallons and what not are made out of, will not break, and the acrylic sheets you buy will also not break, IF they are not supporting each other (basically don't build an acrylic tank yourself, only line an existing glass tank with it).
Just go glass. Not much more needs to be said, if you're really paranoid just silicone a sheet of acrylic at the bottom of the tank.
But in this case, I would reconsider a mantis shrimp not for your sump, but for it's own little setup. You can set up a 5-10 gallon with a G. viridis (lime green) easily.