Gunga Din is an entirely fictional character born of the imagination of the author of the poem.   I wonder what the point is of speculating whether Gunga Din was a traitor, what his name meant or what his religion or social standing might have been among Indian people. He's not a real person and his character was constructed to fit the needs of the author of the poem. It's likely that there was some clumsiness in that characterisation (let's call it poetic licence). You may think that's worth a pound or two of speculation, but the bottom line is that the soldier in the story, a white man, felt so humbled by Gunga Din's noble actions that he felt compelled to articulate his feelings in the final line of the poem - the one thing that most sticks in the mind of almost everyone who's ever read the poem. Look elsewhere in Kipling's body of work if you want to find racism or imperialism. The overriding sentiment at the conclusion of the poem is good.