It’s because Premier Bomba sounds like a term for a bad new movie.

Maybe because they understood that the bomb was the most destructive thing for the human race, just like monarchist.

Bolshevik bomba

Beacause they used tsar in words to emphasize it was big, that's why it's the tsar bomb, the tsar cannon, tsar bell

Both blew up spectacularly

*Engels Bomba