Portable ops is barely canon at this point. Pretty sure even kojima has came out and said he thinks of it more as a spin off than a main mgs game. Plus, given how retcon heavy kojima can be with games he actually wrote and directed, i'd say that shooting something down on the basis it might be canon because a game that basically isn't even canon anymore is kinda silly. I mean ffs the game isn't mentioned anywhere in the legacy collection artbook, was referred to as crap that you should forget about in peace walker, is missing from the series main website's list of metal gear titles, and is basically considered a spin-off by the man who both writes and directs the games.