On the surface, it seems that this line of reasoning is valid and thus justify a need for an official leadership office or position to be the gatekeeper to filter out heretical teaching. But before we examine the reasoning further, do note that this line of reasoning is not tantamount to arguing from the Scripture but one that is on a pragmatic basis. Simply put, even this argument is reasonable, it is nevertheless not shown to be biblical.
On a closer scrutiny, this argument is self-defeating. Even if we will to appoint a person to the task of ensuring the right doctrines to be taught, we are still presuming that this person is doing his job correctly. How do we know that this person has ensured that the teachings are biblical to begin with? In other words, even though this person has been assigned to the task of ensuring the right teachings, how do we know that he is correctly doing the very task he was being assigned to?
Therefore while we can appoint a person to a certain leadership office to ensure that the correct teachings are taught, this appointment itself does not guarantee that the right teaching will be preached. We wouldn't know if the person is doing his job correctly, unless we first know which teaching is sound. And thus the objection to organic church meeting failed. So how do we know whether a teaching is biblically sound?
The answer to this question should not be foreign to the advocates of Sola Scriptura, and it might actually sound simple to you. We know whether a certain teaching is biblical by checking it against the Scripture. Period. If you disagree, maybe you want to take a look at Acts 17:11 and see how things were done back then.
"Now the Bereans were of more noble character than the Thessalonians, for they received the message with great eagerness and examined the Scriptures every day to see if what Paul said was true." ~ Acts 17:11 (NIV)
If the Bereans checked Paul's teaching against the Scripture so thoroughly, why would we not want to check against those who have not written a single letter in the inspired Scripture? If Paul, a servant called of God who wrote the bulk of our New Testament, was not spared from being cross-examined, we will do well not to delegate our God-given responsibility to discern any teachings we hear, to any designated person. Instead, we will do well to study the Scripture so as to correctly discern and handle the word of God.
"Do your best to present yourself to God as one approved, a workman who does not need to be ashamed and who correctly handles the word of truth." ~ 2 Tim 2:15 (NIV)
Thus in the setting of an organic church meeting, there is already a mutual accountability framework in place. It is not a one man affair, but every one's business and interest to ensure that God's truth is preached. Of course, this may not be necessarily practiced, especially when everyone is slacking on this principle. But if such attitude and mutual accountability is absent, then the whole meeting ceased to be organic already. It would be a spectatorship again and not really an organic meeting. May we all strive be an organic student of God's Word.