Basically, it is one man’s opinion against the opinions of others. Ask yourself this question: If Latin was the Mother Tongue of Roman’s, and Hebrew or Araimic was the Mother Tongue of the Jews, and they were writing documents, and considering that the Apostles were not necessarily “Highly Educated” men… why would they be compelled to record anything in Greek?
This site disputes yours:
v-a.com/bible/
And the content of this page casts much doubt on whether or not it was “originally” written in “Greek”:
newadvent.org/cathen/10057a.htm
*General character of the Gospel
Distinct unity of plan, an artificial arrangement of subject-matter, and a simple, easy style–much purer than that of Mark–suggest an original rather than a translation. When the First Gospel is compared with books translated from the Hebrew, such as those of the Septuagint, a marked difference is at once apparent. The original Hebrew shines through every line of the latter, whereas, in the First Gospel Hebraisms are comparatively rare, and are merely such as might be looked for in a book written by a Jew and reproducing Jewish teaching.** However, these observations are not conclusive in favour of a Greek original. In the first place, the unity of style that prevails throughout the book, would rather prove that we have a translation. It is certain that a good portion of the matter existed first in Aramaic–at all events, the sayings of Christ, and thus almost three-quarters of the Gospel.*** Consequently, these at least the Greek writer has translated. And, since no difference in language and style can be detected between the sayings of Christ and the narratives that are claimed to have been composed in Greek, it would seem that these latter are also translated from the Aramaic. This conclusion is based on the fact that they are of the same origin as the discourses. Theunity of plan and the artificial arrangement of subject-matter could as well have been made in Matthew’s Aramaic as in the Greek document; the fine Greek construction, the lapidary style, the elegance and good order claimed as characteristic of the Gospel, are largely a matter of opinion, the proof being that critics do not agree on this question. Although the phraseology is not more Hebraic than in the other Gospels, still it not much less so. To sum up, from the literary examination of the Greek Gospel no certain conclusion can be drawn against the existence of a Hebrew Gospel of which our First Gospel would be a translation; and inversely, this examination does not prove the Greek Gospel to be a translation of an Aramaic original.
I guess my point is this: Just because a bunch of people say it is so, doesn’t necessarily mean its so… From what I have read, I find it difficult to believe that native speakers of one language would automatically write in a second or third language… unless of course they were entirely at home in that language and capable of idiomatic expression.
One was a physician, one a tax collector, and the rest were a variety of occupations…none were linguistic scholars, or highly educated…thus, there is much room for argument as to the “original” language of the scriptures, unless you are talking about the “original translations”…but then there were original translations into many languages.