Quote Originally Posted by paullus
and a single cavalryman from the Sidon stelai,
Which stele would that be?

So while the state of the evidence is such that the Ptolemies could have had some kataphraktoi, perhaps drawn from their Cappadocian/north Cilician cavalrymen, we don't have the evidence that would show it well one way or the other.
Is there any evidence for the use of cataphracts among the Cilicians or Cappadocians in the EB timeframe?

Those same Cappadocians and their neighbors may have been the same soldiers who, in campaigns into southern Egypt in the 3c, used felt armor to cover their horses. Its possible that these felt kataphraktoi persisted, but that's hard to track. If we assume that the felt-armored cavalry in the southern expeditions were in fact the Cappadocian/north Cilician cavalrymen, then we can track their unit down to the late 3c, when the son of a commander on an elephant hunt is a hipparch in the army. But the presence of those soldiers does not necessarily mean the presence of felt kataphraktoi.
But those felt cataphracts are explicitly stated to have come "from Greece."