It probably wouldn't be,but there are way better cages for robos that are very cheap and would hold a more appropriate amount of substrate along with being a bit larger
Cage Duna Multy
Alaska Hamster Cage | Free P&P on orders £29+ at zooplus!
Another alternative would be making a bin cage.This would be fairly similar in cost,but you could make several bin cages instead of only paying for one cage.