"Standards are most dangerous when they are treated as guarantees.
A standard is not a moral statement. In a disagreement about safety margins and speed, it is an agreement about what the system will do under pressure. Without that agreement, you get exceptions by persuasion instead of principle.
In a disagreement about safety margins and speed, the fastest path is to skip the uncomfortable conversation. That buys speed today and inconsistency tomorrow. Keep it calm, concrete, and small; the goal is a move you can repeat, not a speech you can admire. Do not hide the tradeoff in prose; make it two lines so it stays readable when time is short.
W. Edwards Deming is useful here because it forces precision. State the standard plainly, then make the exception path narrow enough to matter. End with one move, not three.