Since precise use of language is so important to you:

> "You can't [...]"

He did, so obviously he can. You mean shouldn't, not can't.

Sure, a slightly irritating turn of phrase, not accurate. I didn't think it would be so controversial to hold terms of art/words with actual scientific meaning to a higher standard though.

If we're willing to be so blasé with 'efficiency' then why not, say, 'functional programming'? If it works it's functional right?

An implied qualification of "you can't [while remaining logically consistent]" is common usage.