It would be legal to capture the rat, with the same rules as capturing a normal robot. However, actually geting it be usefull in a match is another question. Most teams (at least at KSC) deployed their "rats" in the last seconds, often a few seconds to late to make it all the way. I think it would be impossible to make a devide to capture it and get it all the way back to your zone. It would even be extremely difficult.
However, you would be looking at a creativity or other design award
