I believe at the Post Falls conference towards the end +W was asked what the laity should do in the current situation and he replied to read anything on true doctrine, the works of ++Lefebvre, and I think he said that SSPX masses where liberal sermons were preached had to be avoided.
I would consider that red light.
I understood the good bishop in the same way as Zeitun did (and Matthew, too I think).
Yes, a red light for places where liberal sermons are preached.
Yes, that's the point.
Because there's still some noble exceptions, i.e. when some resistance priests (still being in the SSPX) still hold a SSPX chapel, we can go there. Of course, as the good bishop said many times, we've to be very careful now about the increasing "concilar circuмstances", because the Neo-SSPX is on the slide and the situation can get only worse.
Also Machabees' objections to Seraphim's wrong impression are correct: we have yet to see the good bishop's official statement about the leaked answer of Bp Fellay from 15 April 2012. Surely he'll work up this in an upcoming Eleison Comment, but so far he didn't say anything in contrast to Fr. Pfeiffer's newest sermon (Sunday, 10 March 2013).
From all we know so far, Bp Williamson and Fr Pfeiffer are in the same boat, and the brave father listens to the wise judgement of the bishop in the end. No need to divide them virtually.