While it's true that Mercedes would love any opportunity to showcase her sweet vocals, having to spend time with Rachel dictating her life to her was already a painful realization. She let Rachel slide in having the solo during Sectionals because it ended up saving them, but Mercedes barely had a chance to sing once she came back to Glee Club as soon as she left the Cheerios.
She watched as Quinn walked in wondering if Quinn would even have the energy after the pregnancy and giving up Beth. She opened one of her arms and waved Quinn over to come stand with herself and Kurt.
"If we're going along with this, it's high time we show miss prima donna that glee club isn't her showcase. It's the last time I'm stuck doing runs in the background while she and Finn make googly eyes at one another. We're not some disposable extras for her batshit crazy love story. We trusted Jesse for her. How many times are we going to let her mistakes fall on us?"
She turned to Puck with a smirk,
"Hell, we don't need you. My dad was going to take Quinn and I to the beach, far out of Lima. Why the hell would I want to be stuck here?"