Well, yes, people do expect different behaviors from sitting American presidents than from leaders within organizations which have declared war on the United States and is labeled as a terrorist group by just about every first-world country.
Seriously, do you consider this particularly offensive as far as the things that Al-Qaeda has done? They’ve killed thousands upon thousands of people and done everything within their collective power to spread hatred and chaos and tyranny, and you’re upset that they said something nasty about an American politician?