There is no substantial way to date this simply to 250, it is entirely possible to put it mid/late 3rd century, however, the style of the scribal hand more realistically places it anywhere between the late 3rd and early 5th century.
@TheJohnRylands, where it’s housed (
digitalcollections.mancheste…) even places it’s dating into the 4th. Many papyrologists, like
@papyrologyatman, have dated it as late as the 9th century (dates throughout the 7-9th are not uncommon).
No one is denying that Mary veneration has evidence within antiquity, but this is an obvious post-New Testament accretion that takes place in the centuries after the time in the Apostles. Noticeably, it is nowhere to be found in the Bible itself (cf. Luke 11: 27-28) Matt. 12: 46-50).
One can argue reasonably for its development but the Sub tuum præsidium (Mary hymn) doesn’t really come into its own liturgically until the Middle Ages.
Aside from all this, always be skeptical when people put single round dates for manuscripts, dating manuscripts is never that easy and precise (find out how it’s done by going here
wesleyhuff.com/blog/2024/10/…).