No, McGrath that is not true because not all countries give civil partnerships the same rights as married couples.

Then that's where the problem lies, not in a dispute about whether the meaning of a word need to be changed or not.

A civil partnership between two men, or two women, is analogous to a marriage between a woman and a man, but the word "marriage" has till now referred to the latter and not to the former. Arguments about whether this usage should change is a linguistic argument, comparable to arguments as to whether the word "disinterested" can properly be used to mean "uninterested".

As with other linguistic arguments, the decision rests on actual usage. Once the actual usage changes, the dictionary meaning falls in line. (Look up "gay" in a modern dictionary, for example.)