Yup, exactly, for the reasons described in the sibling comment to yours. Doing it this way doesn't even delay mail much most of the time; many legitimate MTAs

Yup, exactly, for the reasons described in the sibling comment to yours. Doing it this way doesn't even delay mail much most of the time; many legitimate MTAs connect immediately to the priority-20 MX after failing to connect to the priority-10 one.