I think the story is that he's a government official, presumably operating on inside information. Thus it's a conflict of interest.

If I'm an official charged with managing public health, and I use my early/special awareness of a virus to stockpile medical supplies, I see that a basically insider trading.

You're also glossing over the fact that his job was head-of-procument. So there's no way that privately procuring PPE didn't conflict with his job of professionally procuring PPE for the government. The fact that he chooses to lie about it presumably shows he knows it's wrong.

Not sure how you could see this as non-firable, potentially criminal.