Errr.....no
the theory that the terrorist attack had been designed to affect the outcome was dismissed by no-one that I recall. (I'm sure you'll have some bookmarks to refute this)
the theory that the terrorist attack DID affect the outcome was accepted by many on the Left and accepted almost completely by the right, but for different reasons.
(Right - the Spaniards appeased the terrorists.
Correct thinking - maybe, but they also turned against the government who despite all evidence to the contrary blamed it on ETA)