There is a deafening silence in Colossians 2.
Paul there is arguing every proper change of covenantal administration from Old to New Testament. He is arguing against the Judaizers, against those who would enforce ceremonial laws on the church, clearly marking the changes from an old to a new economy. It is in that context that he argues that fleshly circumcision is passe, having been replaced by the circumcision of Christ, which is, baptism into Christ. Baptism as an outward sign has replaced circumcision as the mark of initiation into the covenant community.
Paul knows that all his readers knew that circumcision is to be performed on male infants. It's not that Israel was the only nation that circumcised; others in the ANE did it, but as a rite of passage into manhood (in other words, circumcision was at puberty--still is in places today, viz., Africa). Paul, knowing that all his auditors knew full well that Israel circumcised eight-day old males, still proceeds to note that circumcision has been replaced by baptism, recall, in a context where he is pointing out every change of covenantal administration.
Here's the point: if the subjects of baptism are to be different than the subjects of circumcision (only adults and not infants), Paul would have been bound--and he simply would have--in this context to point that out, as a difference between Old and New. But Paul, speaking to Gentiles, is bold to analogize baptism to circumcision, knowing full well what his auditors will conclude about the subjects of such: infants in the old; infants in the new. Adults who are outside were circumcised and similarly will continue to be baptized.
BTW, if the objection is raised that this excludes women, no, Galatians 3:28 makes it clear that there is neither male nor female in Christ and Paul, by example, shows us that women are included in the sacrament of initiation (Paul baptized Lydia).
Peace,
Alan