I don't think it would work out well...shrimp are yummy snacks.
Maybe you could research some larger shrimp, such as bamboo shrimp. I'm actually researching right now, but I wouldn't want to give you poor advice. Some large shrimp have pincers that could tear your betta's fins.
Bamboo shrimp are generally harmless because they have fans instead of pincers and are filter feeders. The only thing I'm leary of is that they are all wild caught, and I try to avoid petstore wild caughts because they are so stressed out