Talk about a complete 180. One minute, the kangaroos and Wickershams are out for blood, and the next, they're totally on board with Who-Ville. They embrace the Whos and recognize their mistake of treating them like they're unreal or not important. In fact, they are all immediately regretful:
"…From now on, I'm going to protect them with you!"
And the young kangaroo in her pouch said, …
"… ME, TOO!
From sun in the summer. From rain when it's fall-ish,
I'm going to protect them. No matter how small-ish!" (221-225)
The kangaroos immediately jump in and embrace Horton's mantra of recognizing people no matter how small they are. To be fair, though, they did figure this out at the very last minute, so the ending serves as a kind of warning. After all, what if they hadn't changed their mind in time? We don't want to think about that.
If we're thinking allegorically, this kind of 180 turnaround came too late for Seuss: he only realized that Japanese internment in World War II was wrong after the fact. And that's why some people read Horton as an apologist's tale. What do you think?