Why do these people get butthurt over drawings of a man that doesn't even exist?
Because they want to bully people.
This shit doesn't have anything to do with religious taboo. The taboo's only on Muslims themselves displaying an image of a Prophet or a holy figure. If it were the obligation of Muslims to prevent the showing of such things under all circumstances, everyone who carries a Crucifix'd be burnt at the stake, seeing as how Jesus is also a Prophet who'll return at the Second Coming to kick Satan's ass and bring the world under Islam.
There are plenty of Muslims who'd like to do such things, but none attempt such things in the West since there's too many Christians who do such things to bully without repercussions. Instead, they settle for bullying Westerners on things that're uncommon enough to ensure they only have to target a small number of people, and save the really nasty persecution for the religious minorities that live in their own countries.
Saudi Arabia, for instance, has more Christians in the country as a percentage of the population than there are Jews and Muslims combined in the US. They just lack any claim to citizenship no matter how long they live there, and lack any human rights altogether when they're from a less fortunate country like the Philippines. Saudi Arabia gets away with this because it's a more powerful and wealthier country than the Philippines.
The core aim of Islamofascism, as is the core aim of all totalitarians, is to bully in whatever way you can get away with. It's the duty of those with the power to fight back against totalitarians to recognize this and fight it to the death.
All that aside, I make absolutely no apologies for the many people out there who's primary concern with Islamofascism is the same paranoia over foreigners that drove Jim Crow, the Trail of Tears, and the Internment of the Japanese. On the other side of the globe, this same paranoia drove the Islamofascists themselves to create the Islamic State, and even the Islamic Republic forty years ago, in the first place.
The solution to this poison is the same for all sides: integration, brotherhood, and the universal defense of freedom of expression. People of all stripes should have the right to be what they want. People who try to force all others to be what they want should be executed.