I can't tell what is subject and what is object in your reply. But if I have your words parsed properly, than I believe you are making a false statement. Let me try again.
My post is valid. In Segwit transacting between
upgraded clients becomes more efficient; there is no increase in capacity for nodes that have not upgraded (or non-Segwit nodes). They are able to receive the data but are unable to validate it. If it is able to validate it then the client it is a segwit node. Not sure if this was changed in any way since the last time I've read about it (there's also a proposal in regards to it by Peter Todd which I've yet to fully read).
(bold not in original)
Please define what you mean by 'upgraded client'.
If such a client is getting a 'capacity boost', the only way this can be accomplished is by that node ignoring signature data. Ignoring signature data in and of itself makes that node dependent upon others to perform validation. Accordingly, such a node
cannot operate in a trustless manner. It is insecure.