What makes you think that Jesus wasn't physically circumcised.
Seeing how Jesus was born under the law, Which means, Jesus had to be circumcised according to the law.
The law of circumcision didn't come to an end until Jesus was nailed on the cross.
I take certain writings & teachings, into serious consideration. In other words, I don't consider all teachings traditional teachings, to be the same, in probability, so forth. Now, I do this with religious writings, like the writings of Josephus, and so forth.
This teaching...now, for example, is a parallel, to the teaching, the fact, that a circumcision, isn't mentioned, generally, in all the Gospels? Perhaps there is a correlation, here, if an actual physical circumcision, did not take place, the author/s did not want to obfuscate this either, fact, or, as the teaching goes, ie a ceremonial non'physical circumcision, to confuse the reader, by writing "circumcision".
There are other reasons why I might consider this as fact, however, just generally, I do make that decision, of which teachings, I believe, or make sense to me, to believe.