Playwright wants to cut 15 minutes after readingtest opening night reviews - ethical concerns?

I'm the production dramaturg for a world premiere play that opened last week. We got mixed reviews - most praised the performances and design, but three major critics specifically mentioned the pacing in Act Two, saying a long monologue "stops the play's momentum" and feels "indulgent." The playwright called me the morning after reviews dropped, pretty devastated. They want to cut the monologue entirely (it's about 12 minutes long) plus trim another scene, and implement the changes immediately. They said, "I can see now that it doesn't work, I was too attached to it." Here's my concern: this monologue is the emotional climax for one of the leads. The actor has built their entire performance arc around it. We're only one week into a five-week run. I've worked on this play for two years through workshops - that monologue has always been there and has always been debated, but the playwright was adamant it stayed. This feels like a panic response to bad reviews, not a genuine artistic revelation. When I suggested we wait a week and see how audiences respond (critics aren't always right), the playwright said I was being "precious about process" and that "the work needs to be the best it can be." The director is deferring to the playwright's wishes. The actor is trying to be professional but I can tell they're hurt and confused.