No, it's not the "opposite of cringe" and it's not an alt-right dog whistle. It just means the person or group is willing to do the right thing, above politics or greed. It's more comparable to Giga Chad, but it's more accurate to say that Giga Chad when used in memes is the representation of a based individual.
Also, "alt-right" is a dog whistle for "white supremacist", invented by a white supremacist to soften the language. Stop using it. Just call them white supremacists or fascists.