That really is a practical thing to have bought right at this moment. Inigo thinks Kitty is pretty smart - in that 'having a lot of common sense' kind of way - though, so he's not entirely surprised she thought of buying it.

"That's great. You're going to look really cool during the next mission!" Sure, that may not be a primary mission concern, but he's trying to find the optimistic view when it comes to anything. "Unless it's going to throw us straight into some odd place where we have to try and blend in."