It was found here in Colorado at the time too, and it was a possibility. We lived in an old Victorian house at the time, and about a week before he got sick he had crawled in the crawlspace under the bathroom to fix a plumbing issue. It's a likely possibility that there were mouse droppings under there. Of course at the time it didn't even occur to us that it could be dangerous. I had barely heard of hantavirus before that.
The way that whatever he had progressed, that cytokine storm thing makes sense. When he first went into the ICU, we had to wear masks, gowns, gloves, etc. They tested for a variety of contagious diseases, but all came back negative. All of the other diagnostic measures were inconclusive.
I got to a point where I just learned to accept that sometimes there will be no answers. If it happened today, it would possibly be a different story.
This COVID-19 thing is indeed fascinating the way it can be so devastating to some, and barely affect others. I am just angry beyond words that we can't all be tested already. Drs. Fauci and Birx talk about these tests becoming available soon. I don't have a lot of faith in that.