Well the minister actually did almost all that could have been expected when asked about the individual who hadn't been tested since November. He'd informed his employer that he had been regularly tested. "So did he lie about being tested?" That as close to being acknowledged without actually calling the person a liar, which is something he should not do.
Why is the testing for MIQ staff and workers not being managed through the facilities like the testing for the people actually in MIQ? How can you have an MIQ testing regime if the entire thing is based on just asking someone if they're getting tested? Weren't we setting up our own security teams and MIQ staff at some point instead of using external companies for exactly this reason?
You can't take credit for a border testing regime when it catches cases but then offload blame onto everyone else when it doesn't. Either your system is good enough or it isn't. In this case, it looks like the entire border testing regime can be outfoxed by just saying "I'm being tested" when you aren't being tested.