You can’t just take away workers right to their own power and self-determination and then think it’s all good if you help them get some of the things they want. That’s not actually being pro-union.
I support unions and workers right to strike but at the cost of potential economic collapse?
Every strike causes disruptions, and the bigger the disruption the stronger the strike. Accepting that workers get to use their power to decide what deal is acceptable is part of being pro-labor, even if it means your life is disrupted.
But if you for some reason don’t believe that labor can engage in big disruptions to show their bosses they’re serious and decide you simply must intervene in a worker-employer negotiation, then enforce the contract the workers wanted. And if you’re not willing to force their bosses to accept a contract they don’t like, then don’t pretend you had no choice when you forced the workers.