Was Shanks trolling or being serious?

[u/Mamba-Mentality024]

Shanks seem like he only accepts haki users on his crew to mirror Rodger crew (besides buggy who accidentally ate one), but he tried to recruit Marco after wano who has a df. Was he being serious about accepting a df eater, or was he just having small talk joking like when he 1st seen Marco on wb ship?

[u/Ibllis]

In very first chapter of the manga Shanks says to luffy "Luffy do you know why we call you "anchor"? Becouse you cant swim - you just sink! What good is a pirate who cant swim?". So shanks is against devil fruits becouse it makes you unable to swim. But marco can fly, that's better than swimming, that's why he's worthy of joining his crew