What is the big deal with someone in the past having made a mistake in what came to be known and accepted as an Ikkar?
What if a certain Rishon thought that matter existed forever? Does that call into question the Ikkar of Ein Od Milvado? For us, this would be deviating from what we know to be true. But he honestly thought this way, and obviously thought that it doesn’t up against the basics, Achdus Hashem, Yecholess Hashem.