It's a joke about how the safety system on the car works. From another comment in this thread:

Based on what it didn't cut through, his finger should have been safe but apparently Tesla designed the thing to keep increasing the pressure if it detects resistance each time until it can close, which is absolutely baffling. I don't know of any other safety feature that turns down the safety the more it activates. The fact that it reacts to the exact same conditions differently each time should, in itself, be deeply concerning for any safety feature.