Permit me offer this: Acts 16:1-3 says Timothy was circumcised to show he was actually a Jewish convert and not a Greek as his father was. Since it was not a sign of putting himself under the Mosaic Law again Timothy was simply following a custom that while not demanded of new disciples neither was it forbidden for as Paul says at Gal. 5:6, ‘neither circumcision nor uncircumcision mean anything’
I agree. I also do not condemn brothers and sisters who do observe, today, "days and weeks, feasts etc." As long as those observances do not replace Grace through faith, we are told not to bother each other about it.