"with MS as the publisher" is the key part here, of course MS is not going to be the publisher for the PS4 version.To me, the highlighted reads as confirmation of console exclusivity. Insofar as it isn't being developed for any other console - the focus is on bringing it to PC and Xbox One - that is what the second part of the statement means. The person then replies that it isn't clarifying (even though it is a definitive yes statement followed by reasoning) to which they reply that they got nothing for us besides that.
MS being the publisher is "allowing them to bring it to xbox users faster and solely work on that", after that they are free to work on the ps4 version and bring that out with another publisher.