It’s to quote specific words which are pertinent to the threat level implied, rather than the entire post.
Extraordinary claims require extraordinary evidence.
Extraordinary claims require extraordinary evidence.
Edit:
By the way, what do you mean by threat level here? And FWIW, here I could have used quotes without being rude.
Also: if you read that sentence again you'll probably find that it wasn't just the use of quotes but the sentence that as a whole that made it stand out as rude.
Suggesting it is an extraordinary claim, and would suggest an extraordinary threat to all AWS accounts. This seems very unlikely.