OK, perhaps I need to clarify what I meant by "viral". I did not mean, "pernicious" or "evil". I meant that the license propagates itself through its descendants. Perhaps I ought to have used the word, "genetic" as a metaphor, rather than viral. In any event, I did not mean to suggest that GPL was in any way evil or wrong. I agree with you that copyright is the culprit, not GPL.

I'm not sure I explained my point fully. The concept of "derivative work" is the so-called viral property and that comes from copyright, not the GPL.

No, you were quite clear. I can't lay the blame on you for this. I was simply using a very badly-conceived metaphor, one with negative connotations and that doesn't come close to describing the actual facts concerning the GPL. If anything, GPL would be more like a vaccination against the viral qualities of copyright.