Indeed he sounded like an ass, but “heated” and “diverting” and “both thrown off” sounds a bit more than just tossing water.
Bottom line, instead of ASSuming she can just back into someone, she should be the first to ask if it is OK to recline. [You said she paid money and is entitled to be comfortable (hah, on airlines these days?) - so why not him?]
Sorry, but it is true that they recline more than is really "comfortable" for the next person. I guess that is if you are on a half-empty flight and it doesn't matter.
I already went over the etiquette rules in my first reply.
He could have politely asked her to only recline slightly, not totally. Instead, he came PREPARED to be a b______ with his Knee Defenders. So, your logic doesn’t wash for me. She has a right to recline. Perhaps they could have swapped seats, but with a darn Knee Defender sticking in my back, I wouldn’t feel like compromising either.