Indeed, @w means no additional end-of-sentence spacing in TeX (essentially @w = \hbox, and there is no stretching and shrinking inside an \hbox). Whether the space comes from an SPC character or an EOL character is immaterial. Presumably it should be the same in makeinfo.
I'd have to try to find the previous discussion with Patrice to see the context to say more, and I can't do that right now, sorry ... -k
