Very true. It remains a prooftext against scripture divorced from the Church as pillar and foundation of truth, my original point.
The verse is about knowing how to behave in church. It mentions, in a way that COULD be interpreted a couple of different ways, the pillar and ground of truth. But that pillar is subservient to the Word. The TRUE CHURCH can not be divorced from Scripture, for Scripture gives the Church its life. Where things/people identified as the church deviate from Scripture, they are not being a pillar and ground for truth. The pillar and ground are inseperable from the truth and the truth is the Word of God.