It’s not like the Finnish white regime invented the concept of using liquor bottles as thrown improvised weapons. Both sides of the Spanish civil war a few years prior (including Republic-aligned communists and anarchists) used them in abundance. But because the Finns mass produced them and the Western public (namely Britain) was sympathetic to the Finnish “war against tyranny”, “Molotov cocktails” stuck.
Since then however, Molotov cocktails have become symbolic of under-equipped guerrilla forces and protest movements across the political spectrum, but mainly among left wingers and socialists. Even anticommunists would sooner associate them with anarchists than based Finland.
I guess the poster can replace the Molotov with an AK but that kind of undermines the “call to arms” message of it.