He's not wrong. Look at the amendment that banned alcohol. It was repealed through another amendment.
The Constitution is meant to be updated and changed with modern times. What he's meaning to say is that despite Republicans (who don't even understand the fucking document) believing the Constitution is set in stone, it's actually meant to be changed regularly.
So when the republicans are in control and demanding the Constitution be changed to protect the sanctity of marriage and ban abortion to protect the life of children and stop child abuse by baning gender affirming care you would be totally on board with that because rules need to be updated or else we would still be in the middle ages and still have kings and slavery