I’m ashamed to say that I tried MAGA. I was relieved when it wasn’t accepted.
Try with a final E. Or did you get that one?
For today, AGAMEMNON wants them to accept GNOMON, but of course, it still isn’t.
I did but detent and detente are different words.
It didn’t accept
GAMMON
I tried that as well. Too British?
Maybe? It was accepted a few times so who knows.
I only tried MAGNETO as a joke - I didn’t realize it was a real thing.
That word sounds like the name of a villain in a superhero comic book.
You obviously didn’t grow up on a farm that had pre-1960 John Deere tractors!
Quiet day today, nothing doolally.
Yeah, I tried that one, too. I’m just missing the hardest word, one that I’m sure I don’t know.
ETA: Finally guessed the right combination of letters. Considering some of the words he disallows, I’m pretty surprised this one is considered common.
Guilty as charged.
No AHOLD.
I tried it too and it turns out that the standard way is as two words
Merriam Webster, Cambridge, Collins, and Oxford accept it without commentary. It’s primarily a US usage.
I thought it was in poor taste to include
MEGATON
during the week we are commemorating the 80th anniversary of the Hiroshima and Nagasaki bombings.
(I agree it was weird they didn’t accept
MEGATONNAGE
).
I’ll note that they RUTHlessly ignored TUATARA and CAOUTCHOUC. 
Funny time to exclude the word AUTARCH.
Also, I tried auroch, but it wasn’t accepted.