Pardon me, I've only been studying textual criticism for 5-6 years, and I've never heard of this particular "measure". When studying variants
Therein lies the problem. What I said has little to do with textual criticism. With love, fellowship, and no ill intent I encourage care be taken not to fall prey to "tunnel vision, confirmation bias, and/or the fallacy of false equivalence.
When the canon was established textual criticism was at best in infancy and was definitely not the sole means of discern what writings were inspired when deciding the canon. For example, Theo, when were the seemingly added texts added? There have been different "canons" asserted at different points in Christian history but the current canon was formally accepted in the fifth century. Were the Matthew and John texts added afterwards? If not then how and/or why did the rigorous and prayerful investigation and debate of the fifth century accept these passages?
It was not because of questions about textual criticism.
If the basis of the inquiry and skepticism(?) is something learned through the study of textual criticism (facts upon which I can join
with you in agreement) then take care not to use the wrong tool for the job. A screwdriver can be used as a hammer, but that is not its intended purpose. Perhaps that's a bad analogy; textual criticism is designed in part to determine authenticity but it is not the sole measure for answering the question of this op.
If the text was added sometime after Matthew and John wrote their gospels but before the 5th century decisions than when, and how, and why? Since the only possible answer we might entertain is scribal addition and absent any evidence that is speculative. I don't want to enter a slippery slope but what is the remedy? We remove the questionable texts? Who gets to decide that? Are we to call for a new council and all abide by its decision? This was easy when everyone was RC, but in today's Christendom finding a consensus just to call for a council is going to be a problem; it is going to, ironically, manifest the problem upon us. Then what? How do we pick the members of that council? By what criteria (I would respectfully suggest tunnel vision is disqualifying) are we to select those arbiters? Are we going to have David Jeremiah, John Piper, the current Pope or the current Patriarch (or one of their selections), Justin Welby, J. D. Geear, Gary Demar, Max King, John Hagee do the selecting for who sits? No, of course not. We'll try to pick experts in
the various fields of relevant study. However, unless they also come with the pastoral sensibilities and are not only academics that's still gonna be a problem. Once both a council and the practice of modern councils established then what will prevent further questioning of further canon on other grounds? Are we to believe all of the above has not already been considered by those higher in the food chain than internet forum posters?
The Bibles I use in my daily practice (NIV, NASB, ESV, and on occasion the KJV) all have notes or markers in the text telling me the questionable passages may be additions. I routinely examine the Greek, and often do so looking at the variants. In other words, this isn't a secret. No one's trying hide anything, deceive the readers, or in any way pretend the question doesn't exist.
Until there are better alternatives isn't the current condition (marking the text) the proper response? Isn't that better than removing parts of the Bible? If that is the case then I do hope you're not a KJVOnlyist

.
The op is a great question but if the answer to "
What are we going to do about what remains a matter of speculation?" is "
I don't know" then let's make sure we're not creating controversy in our own impotence or for the sake of the controversy itself.
And Theo, I read where you're telling others they are coming across as arrogant and ignorant. Not only is this a violation of the tou but when you appeal to your own studies of textual criticism you come across in the same ways. I will be reporting the post. Do please make a conscious effort to
keep the posts about the posts and not the posters. I trust everyone here in the conversation can abide by that simple standard.