Drawing the line so low, even personally excluding his own daughter, yet he remains composed, showing no concern at all.
Indeed, there's really nothing to worry about.
From the moment he decided to eliminate the Mingshan Sect from the competition, he had this all planned out, ready to use it as needed.
As for the oath sworn by his daughter and Shi Chun, claiming that Shudao Mountain wouldn't compete for first place against Mingshan Sect, or else he'd die a miserable death—
He doesn't believe he's broken any sort of vow. Has Shudao Mountain competed on the same stage as Mingshan Sect? You don't even qualify to participate. That's not something Shudao Mountain can dictate—it competes with others, not with your Mingshan Sect.