She did say she didn't have the souls to deal with Marco. She needed them for the Kaido fight and against Marco, it was made apparent that he's very dangerous to her homies. Let's not forgot that she used quite a bit of her own soul to make that homie army. Marco was overall a nuisance to her and his ability to stall is a bitch to deal with.
She overpowered him rather easily once she got the least bit serious, when they clashed she was more focused on having him move out of the way instead of fighting him, but once he hurt prom, she got serious and straight up overpowered and chocked the man. I dont know why people seem to ignore that part.