In the second paragraph of the "Tales of Foreign Lands" section of the quest guide for Myths of the White Lands, it states:

 

In order to get to the Land of Snow, head to the basement of the Wizard Tower south of Draynor and speak to Isidor. Once you remind him of the teleport phrase "Ectosum glissendo", he will send you to the Land of Snow.

 

 

 

It is worth noting that you can also get to the Land of Snow simply by talking to one of the Head Snow Imps from the Christmas event. The Imps can be found North of Falador, North of Rimington, or North of Lumbridge.

 

 

 

EDIT: I'm under the impression that a bit more proof other than my word would be helpful, so:

 

I agree with you entirely, and was in fact going to add this. Then the author pointed out that the holiday event snow imps would be gone in a few weeks, and the wizard would be the sole source. So it was decided to leave it as it would eventually be.