In an answer to a question in SE I read the sentence with the pretension above.
I think this can be easily be counter-proofed by many examples of Bach’s music and especially in his figured bass.
Here's the first page that Google found when searching for 'Bach chorale'. See the suspension? Bach certainly wrote suspensions. I wonder what the SE meant?
OK, now you've added the link. He's discussing not whether Bach wrote suspensions, but whether Bach thought of them as such, as modifications of triad-based harmony. A fair point. It's good to remember that harmonies can arise from the combination of contrapuntal lines. Guitarists in particular can fall into the trap of looking at chords as entities, ignoring the voice-leading element.
We can't look inside Bach's head, but my opinion is that Bach was quite aware of the patterns in homophonic harmonies, as well as being a master of counterpoint. I think I disagree with the answer you quoted. But the opinion stated isn't idiotic.
It is not true.
The linked answer is bad and I down voted it. The best way to deal with that answer should not be to "edit" it, but down vote it for all the bad information it contains. The person didn't know what they were talking about. It reads like cursory knowledge of the topic distorted into an authoritative answer.
I added my own answer which I think is better.