This article is an example of “gas lighting”, lying about what happened and accusing you of being a liar or bigot or crazy if you object to his lie.
Anyone objecting to Dr Seuss in 1980 would be a right wing anti Semite objecting to his liberalism and for being Jewish.
That could be true, or the person objecting to Dr. Seuss in 1980 could be a leftist anti Semite, or a member of the Nation of Islam or a similar group who happened to be anti-Semitic (and anti pork).
In this case the author's mother seems to be opposed to pork which is certainly an unusual religious belief among common Christian congregations in the southern USA. To my knowledge only Seventh Day Adventists abstain from eating pork.
You are correct however in saying that in 1980 people opposed to Dr. Suess would have most likely been opposed to his generally liberal views.