A diocesan affiliation doesn't bother me one way or the other. The Object is to have the Traditional Faith preached and taught. The evidence is fairly clear, that a diocesan affiliation didn't bother Father Wickens all that greatly.
With regards to the SSPX, if he was that enamored of them, he could have joined them, he chose not to, instead praising the good works they did, but remaining at a respectful distance.
I would think that somewhere along the line the calculus involved would take into account ones personal measure of the Priest, rather than a 'diocesan, bad, Not diocesan good' tone.