Pour it a couple of inches from the water. I was dumping it at eye level like an idiot, for a long time, getting splashed and sucking it all in.
Until the yard is cleaned up, the pool will be dusty. You use the chemistry to prove the difference between unsightly and unsanitary.
At any time if you suspect more than dirt,
Overnight Chlorine Loss Test to remove the sun from the equation. If you lose FC with no UV/sun, something is brewing. Don't come ask if you should, come tell us you are awaiting the results and we'll chat about idiot in laws while we all await with you.
If you pass, and can attest that the FC stayed free and clear above minimum going forward, you'll be on good ground to say it's just dirty.
Welp. Life experience has taught me that if he wasn't having a better pool than you, it would be cars. Or golf. Or his career. Or all the above. Treat him like the pool store. Smile and nod and let it go in one ear and out the other.