That's a hypothesis amongst others, but it's just that, with essentially no hard evidence backing it up.

And it flies in the face that the earliest known knitted artefacts are from centuries later, to say nothing of knitting spools which they would predate by some 1300 years.

This hypothesis also lacks a lot of explanatory power e.g. why did some of them find (and take) room in coin hoards? Why have they been found all over Gaul, Germania, and Britannia, but not Italy, Hispania, or the eastern empire?