TQO said; the WT doesn't claim that they are infallible/inspired prophets at all, merely that they are guided by Gods spirit, and that they may be wrong when making an interpretation of prophecy..
Then why would they take such a hard line on anyone who may not agree with their interpretation of prophecy if they admit in advance that they may be wrong?
If you don't agree 100% with their 'interpretation of prophecy' then one is labeled an 'apostate' and cut off from family and friends. Why? Seems a bit harsh for a group who freely admit they could be wrong about things.