It is wrong to say that a person is intelligent just because he is able to convey his thoughts in English. Yes, English is a body of knowledge, a facet of intelligence, but to use it as the measure is unfair. I know a lot of people who have difficulty communicating in English but are very much dexterous in solving lengthy equations. I know teachers who teach in dialect because students understand them better that way.
Yes, to speak and understand English is to be abreast with globalization. English takes you everywhere. But the point is, one must not be prejudicial. One who speaks, who is able to speak, is not automatically the most correct person in the room. Intelligence is totality. And to measure it via a facet is myopic.
But then again. It all boils down to your definition of intelligence.