Speaking for myself only; I think it was an irrelevant and stupid argument that Rick somehow allowed himself to get led into ...sort of like Rick's personal views on contraception. He just shouldn't go there!!!
Rick should talk about the economy, the price of gas, balance of trade, monetizing the debt, Iran, ...the list goes on and on; but it doesn't (and shouldn't ever) include discussing why a traditionally Hispanic island's inhabitants should learn to speak English ...which most of them already do! ...plus they also have a relatively Conservative Republican Governor; Luis Fortuno.
What should Rick do if asked questions that do not concern the economy, price of gas, etc. ignore them? Plead the 5th?
If you accept that a candidate should honestly attempt to answer questions put to him, how should he have dealt with what surely was a question apparently concerning many in PR, which is where he was campaigning?
There're are some poster here who would criticise Santorum for standing during the national anthem, but as another poster asked, what really was wrong with the answer he gave here?