Dear Patrick,
Thank you for your message. I am (we are) always interested if you find mistakes and happy to answer questions about the NA or UBS editions.
Concerning your question, I also did not find evidence of this reading in Origen's works. As you mention, this citation is not in the UBS4, but was in the UBS1 (1966), 2 (1968), and 3 (1975). The apparatus data from these earlier editions was probably taken from the NA25 (1963), which indeed has a citation of Origen here. The first Nestle edition to cite Origen here was the N13 (1927). I do not know for sure, but the N13 could have used the data from Souter's edition, Novum Testamentum Graece (1910), which has a citation of Origen here. Souter's reference to Origen is the earliest I have seen in the limited search I was able to do. Neither Tischendorf nor von Soden (i.e. the sources that Erwin Nestle states he used for most of his patristic evidence) have a reference to Origen here.
So, to try to answer your question, Metzger was probably using the apparatus of the UBS1 and /or UBS2 when he wrote the Textual Commentary (first ed. 1971), and this citation was probably not checked when producing the second edition of the Textual Commentary (1994), which I suppose is the edition you're using. The citation of Origen is no longer in the UBS or NA editions, probably simply because it is either inaccurate somehow or does not exist.
If you are really keen on finding the source, I would try to find the sources of Souter's information (which could be Minge's Patrologia Graeca series).
I hope this helps. Please feel free to follow up with more questions.