It's fine and defensible to oppose (or support) patents, but the "when it is about software, particularly so" is just a geek engaging in irrational thinking.
No, it is entirely rational to fight something you don't want.
The chemists, for example, seem to be ok with a world ruled by lawyers, or where, after having a good idea, you end up owing someone a shipload of money just because someone has a patent on it. The chemists can get it unlubed in the if they are ok with that. It seems they are a spineless bunch.
[...]irrational thinking. The same way the suit rubbing his hands together in greed because "it's on a computer" is.
Perhaps your idea of what is "rational" is severly limited and crooked. Here is your mistake: that greedy suit is being rational, because the "it's on a computer" is just an argument he uses for his own self interest. Just like that incredibly narcistic "why should I think if i don't get to become rich for some stupid idea" line. The point that should matter is that he or she is a greedy asshole that wants to take your money away, wants to enslave you, and deserves something entirely different from being rich and successful. What is important is that he or she must be stopped.
That whole line with "being rational", especially when the arguments are as stupid as they are when people favour patents, is quite often just a smokescreen and a maneuver to make you think in a way someone else wants.