You say, "30-60 years later while witnesses and enemies were alive is the gold standard of history." Yet the very scholars who study the New Testament professionally acknowledge that the Gospels are not straightforward eyewitness memoirs. Raymond E. Brown explicitly states that Matthew is best understood as a Greek-speaking Jewish Christian who drew on Mark, Q, and other traditions, not necessarily the apostle Matthew himself. Regarding John, Brown says the Gospel likely passed through a Johannine school and may even have been edited by a later redactor. So the issue is not simply when a text was written. The issue is who wrote it, what sources they used, and how those traditions reached them.
Your argument also assumes that writing something down automatically guarantees historical reliability. That is historically naive. A written story can preserve accurate information, but it can also preserve embellished, theological, legendary, or mistaken information. Historians do not ask merely, "How old is the manuscript?" They ask, "Where did the author get his information?" Luke himself tells you he was not an eyewitness and that he relied on traditions handed down by others. In other words, your own Gospel already contains a chain of transmission before a single word was written.
The irony is that you mock oral transmission while depending on texts that emerged from oral transmission. Mark was not dropped from heaven as a completed manuscript. Matthew was not written the day after the crucifixion. John was not a courtroom transcript. These texts emerged from decades of preaching, teaching, remembering, interpreting, and transmitting traditions within Christian communities. That is precisely why scholars spend so much time discussing sources such as Mark, Q, Johannine traditions, redaction layers, community influence, and editorial activity.
Even worse for your argument, Raymond Brown openly discusses disputed authorship, Johannine schools, editorial additions, and the possibility that some New Testament writings bearing apostolic names were not actually written by those apostles. He even devotes discussion to pseudonymous Pauline writings. So while you are mocking hadith literature as "folklore," New Testament scholars are debating anonymous authorship, redaction, source theories, community traditions, and pseudonymous compositions inside your own canon.
And then there is the double standard. When Muslim scholars preserve chains of transmitters, biographies, dates, teacher-student relationships, variant reports, and evaluations of reliability, you call it "oral gossip." But when a Gospel appears without an isnad, without named transmitters for most of its material, without biographical scrutiny of the intermediaries, and often without certainty regarding authorship itself, suddenly that becomes the "gold standard of history." That is not historical methodology. That is special pleading.
The reality is that historians care about sources, transmission, and verification. Hadith scholars spent centuries documenting exactly those things. By contrast, for many Gospel traditions we do not know who transmitted them, how many intermediaries existed, or how the information moved from eyewitnesses to the final author. You cannot dismiss isnads as worthless and then appeal to texts that usually provide even less transmission data. That is not an argument; it is a contradiction.
So no, this is not "1st-century written ink versus 9th-century gossip." It is a comparison between a tradition whose transmitters were scrutinized individually and a tradition whose sources often have to be reconstructed by modern scholars through literary theories because the chains were never preserved in the first place. The fact that a story was written earlier does not magically answer the question of how the story reached the author. That is exactly the question hadith criticism was designed to address.