It wasn't just that people would've never tried tomatoes ...there was a strong campaign of thought working against those who otherwise would have likely been willing to give the tomato a try.

It really depends what the campaign is.  If they said the Italians were extra virile as a result of eating tomatoes ...everyone would've probably been eating them long ago.  But, that was not the case.  Once people began to die ...instead of realizing it was from the pewter plates, they effectively convinced most people that it was the tomato.

So, two things worked against the tomato.  There was no knowledge of truth, and there was a very effective negative campaign.