
Was outlined by Oda already in an SBS.
It's not that he's too tired to move, it's that he knows he's right next to his crew so he trusts them to preserve energy.
WHILE FIGHTING KAIDO:
He's all alone, only he can take down Kaido.
He restarts his heart right there and then and activates G5 once more.
WHILE ON EGGHEAD:
He lands right next to his crew.
He trusts Franky and Sanji, there's no need to waste energy so he just lets himself be carried around.
No I don't care about how he looks if that's a G5 gag, the core idea of the drawback is still the same.