block size – re: minimum transaction sizes and blocks

I see there is a similar question here:

What are the minimum sizes for transactions and blocks in Bitcoin?

But the response provided may not be correct in light of the fact that "a valid transaction requires at least 100 bytes" or something is missing here. See checklist # 6.

If it is relevant to the minimum size of the transaction, my question would be if this standard were introduced after or before the response.
Also, did the answer provider care to distinguish between valid transactions and invalid transactions?