Well, unfortunately, this is a common occurrence when such a traumatic and unfortunate accident happens involving a wild animal. Especially when it involves mass amounts of media coverage (and when the loss is of someone so loved as Irwin, that coverage is predominantly negative).
The public as a whole has deep seeded misunderstandings and irrational fears of many wild animals - especially those which are right in our own "back yard", and not in some remote jungle or roaming in the far away savanna. Oceanic animals take the brunt of this hostility because so few members of the public have ever actually interacted with these animals, or cared to educate themselves on scientific and statistical facts. Not to mention the media thrives off of "Entertainment", so about 90% (No joke), of what you will ever hear or see from the majority will be inaccurate and instigative.
Though yes these animals can be dangerous - as all animals can to some degree - they are not aggressive by nature, nor do they pose any threat to humans under responsible, social encounters. The incident that took place with Steve was a tragedy, BUT it was nothing more than an accident. This animal was not "out to get him", and the strike from it's tail was not "Aimed to pierce his heart". If you believe that, you are ridiculous.
To understand this accident, one would have to have all the pieces of the puzzle and know that ultimately, the animal was (innocently) spooked, reacted according to survival instincts, and Steve's positioning just happened to be that 1 in a 1,000,000 positions that landed a fatal blow.
For individuals to take it upon themselves to seek out and murder such beautiful and peaceful animals, in their attempt to "protect" others and "avenge" Steve's death is just disgusting, and down right ignorant and self-serving. A case of "Little Man" syndrome and uneducated pompous fools trying to be a "Hero".
Showing your respect for someone so dedicated to conservation and education would mean following in their footsteps, and taking it upon yourself to carry out the work that they dedicated their lives to.
There will always be idiots to battle, but that is why we won't ever stop. We simply cannot. Stupidity is more toxic and destructive to our environment than any natural disaster or man made pollutant.