Ashraf, it should be obvious to anyone that Jim McGregor took on a very personal tone in his article. He wasn't so much trying to set the record straight, as he was taking a personal jab at you (and others like you). That much is clear.
But as you said, you stated your assumptions, and your points were well reasoned, so I don't think you have much to worry about. The only credibility that will be called into question will be on those people who come across as having a bone to pick with someone, rather than the truth-seekers that readers and investors are really looking for.
You may need to offer a Mea Culpa for jumping to conclusions, but I think your readers will appreciate the consistency in your predictions, and your continued pursuit of the facts.