The linguistic situations in Quebec and Puerto Rico today are quite different. Fewer than 10% of Puerto Ricans have advanced fluency in English, and there is no mass of English speakers trying to move there. Most Quebeckers have working fluency in both English and French, and there has been a sharp decline in the number of English-speakers since the 1970s.
There is no reason for anything like Bill 101 in Puerto Rico because the Spanish language is not endangered there. If Puerto Rico were to be admitted to the union, they should be able to do so as a predominantly Spanish-speaking state. The American system has been multicultural and multilingual since its founding.
The island obviously doesn't have a land border with an English speaking U.S. state(USVI are separated by ocean).