As Paul said, there is no official language in the US. And to provide some historical perspective, plenty parts of this country were inhabited by non-English speakers (including Spanish-speakers) long before English-speaking Europeans moved in. In every generation there is backlash against the biggest group of "others" who are supposedly threatening the American Way, and ironically, they later can turn into the ones protesting the latest group of "others." Even if first-generation immigrants never fully assimilate and become proficient in English, the odds that subsequent generations will not assimilate or be able to communicate in English is ridiculously small. On the other hand, the odds that those subsequent generations will lose touch with their family's cultural heritage and heritage language is much, much larger. Honestly, do not worry.
Meanwhile, my question is, what is wrong in and of itself with providing assistance to help people understand and communicate with others?
I often wonder how many people that protest language assistance have ever moved to another country where they knew nothing of the language and, as an adult who is also working full-time, tried to learn a new language. It's hard. It takes time and energy and a lot of effort. And it doesn't happen overnight. And in the meanwhile you will be very, very happy to have a little help figuring out what is going on.
Should people learn English in the US? Absolutely. It will help both them and others immensely. Should we begrudge assistance to people who are not there yet? Absolutely not.