Yes it is. Opening up your computer to every Tom, Dick and Harry that wants to put something inside it is no more safe for your computer than sleeping around is for a human.
Why do you think they call it a virus?
sigh
Let's look at the obvious straight off the bat, ok?
I can test anything coming into my computer in a matter of seconds - can't do that with people.
I shut my computer off for thirty minutes or more - can't do that myself. If I stop functioning, I die. If the machine stops functioning, I restart it.
Human disease kills. Computer virii destroys data. Computer data can be backed up (like mine is) and restored. Human life cannot be backed up and restored.
Not that my opinions matter - obviously, you know exactly what you're talking about, and I'm just a poor inept end-user.