I don't believe you have ever attended or seen a protest in a country that does not speak English. English language signs are common in both right wing and left wing protests. By common, I mean that they are gonna be present, if not in big numbers, than in small numbers, basically at any protest.
Why?
Over 150 countries around the world have English as a required subject in school. Everyone learns English now, and in a few generations the majority of the world population will probably be at least slightly bilingual in English. It is the global auxiliary language. When a socialist from Japan and a socialist from Brazil want to talk to each other, what language do you think they use? Do they think they just refuse to use English (the only language they have in common) bc America is the Great Satan?
To assume that any message written in English is necessarily directed to Americans is just absurdly Americentric thinking
Do you think these pro-LGBT protesters in Thailand and Japan are seeking American military intervention? Or do you just think they want the whole world to know what they are saying?
Yea and I'd also note that this is supposed to be like fluent or near fluent speakers. If you include the number of people with at least some basic level you are probably looking at a number that's maybe nearly double that I expect.