Please re-read my explanation. For C-14 dating to work at all, exchange of carbon with the outside environment in a given sample (such as a chunk of wood) has to stop. That's what happens when an organic sample is dead and buried. So long as carbon exchange is occuring then the 'clock' for dating hasn't started, and the sample can't be correctly dated.
C-14 is produced by cosmic rays impacting N-14 in the upper atmosphere. It is not being produced underground*. So buried samples that have measurable C-14 must have been buried within a thousands-of-years timeframe (as measured by the C-14 remaining), not millions.
*(When this began to become public, some people suggested C-14 could be produced in situ in the geologic record due to uranium decay, but it was investigated and found to be an unworkable solution because the method only produced infinitisemal amounts of C-14. The sample would have to be over 90% uranium to produce the measured amounts of C-14, and as one scientist drily noted, "You wouldn't ordinarily call such a sample 'coal.'")
That will date the sample in question. To use that as evidence of a young earth, you have to assume that nothing else can be any older than that sample.