No it is more than a mistake. There is a reason ancient cultures would kill people for doing such things. Our modern society has taken some of the edge off the consequences of this particular "mistake". Though the costs are more hidden now, we don't have "street urchins" anymore.
On the other hand the costs are still significant. There is a reason that the term "bastard" has such a negative connotation. It isn't just that a person is of questionable parentage. People raised outside of a viable family structure tend to revert to barbarism.... aka act like rotten bastards!!!
With that said, and it should be, we should avoid sounding judgemental. We all do awful things. Hate the sin not the sinner? We cant go back in time, so let's deal with what can help the situation. Making Shaun feel like an asshole probably won't make him very productive. I think that is all MJ is saying.
So Shaun, you did something really reckless and awful. Other people will probably pay the consequences of your actions long after you have passed. With that being said, there is an whole lot you can do to lessen the damage of your actions. You need to be apart of that child's life. You need to learn to masturbate (stop having children!!!) and start thinking about things like marketable skills (getting a decent job) and what kind of father you want to be... what kind of life you want for your child.
I hope you choose well.... so your kid doesn't rob me in 15 years or try to hand me cult literature.