wouldn't rule out a Labour shift towards a second ref, given the support among their members.
I think 'triangulating' is giving them far too much credit. They are between a rock and a hard place on Brexit and are consequently trying to avoid committing either way. At some point they're going to have to jump, but they're hoping that things go sufficiently wrong between now and leaving that they can dress it up as an act of principle rather than a cynical and opportunist bit of politicking.
If that doesn't happen, a general election between now and us leaving is the last thing Labour want as it would force them to nail their Brexit colours to the mast and lose voters from one camp or the other.