theproclaimers said:
Playing bass guitar with a bow, while unconventional, is a legit way to play. Plenty of players have used it to great effect and there are many examples on YouTube. Therefore, I don't think the "you're doing it wrong" tag is warranted here.
Even if it's technically viable and used in the real world, the pose and commentary hint more at that it being a you're doing it wrong-esque pardoy of Soyo playing a "normal" bass like in Episode 9 of the anime (asset #23136321). Without this context you'd be correct, but I think it's important in this specific instance.