No, actually the only thing that Porygon had to do with the seizures was that it happened in it's debut episode, however if you look at it Pikachu was the one that caused the flashing lights, not Porygon, however since Pikachu is the mascot they couldn't banned it so they decided to ban the Porygon line just because it happened to debut in that episode even though when you actually look at the episode Porygon didn't cause any of the flashing lights it was all Pikachu.
Also I have to wonder they didn't bother to look over this episode and make sure there wasn't anything wrong with it because if you look at it, it should have been brought to their attention that having different color flashing lights flashing that fast wouldn't be such a good idea, I mean did they not understand that flashing lights could do that, because if they did then I can't imagine why the episode would be allowed to air with the light flashing that fast.
Also I'm pretty sure it would be possible to come up with a plot for a Porygon, Porygon 2, and Porygon Z episode without flashling lights, I mean it's sort of ridiculous for the Porygon line to get banned for something it didn't even do.
I mean if you actually watch the episode you would see that Porygon itself wasn't responsible. I mean lets look at this did it launch the missile? no, did it destroy the missile causing the flashing lights to occur? no, Pikachu was the one that destroyed the missile and caused the flashing lights, but if we look because it's the mascot Pikachu gets a free pass while Porygon got banned just because it was debuting in that episode, so I don't see how the Porygon line is at fault here.