Unfortunately I bet that 90% won't even reach at that part and just ragebait based on the title. The golden rule of modern age is always do the disclaimer as soon as possible.
I'm truly curious to know why would this be rude, seriously. Maybe it's a cultural mismatch.
For me ragebait and rudeness are things like: "X sucks, use Y", "If you aren't doing W you're losing money", etc.
He never said that Kafka sucks, nor anything related, obviously you can't replace kafka with only two signals. I'm asking with all politeness as possible, I just wanna understand what other people consider improper behavior