She’s right imo. I’d much rather someone tell me there’s nothing in stock or they don’t know then fluff around with corperate scripts. Heck I’d get good feedback from customers telling me as much. I still maintain this even when I email at my day job to date.
I understand needing tact sometimes and “reading the room” reaction wise when crafting a response; sometimes being too straightforward can also be upsetting. (AKA rude)

↓ Transcript
Ash tells the customer "Bad news is that we are still out of eclairs but-"
Ash turns to Flori. "Hey Flori, can we reserve some for the customer tomorrow?"
Flori leans in, her face sour. "No need. We'll be fine."
She turns to the customer, he smile lifting to customer service mode. "We'll have them in first thing in the morning!"
Ash's grin is strained as Flori hovers nearby. He thinks "Is this really how we treat people?"
The customer leaves, not entirely confident in her expression after being served.

Ash's strained expression remains. "Oh, can we not reserve things for customers?"
Flori returns to her usual straight backed, formal stance. "Word of advice. Just get to the point. Ignore those silly corperate training videos. Telling them bad news they already know just comes off as rude. Customers will thank you for your honesty."
Ash looks unsure, muttering "But the videos say..."