Renaming the Langevin block is not an erasure of his role in history and our current culture  - as the discussion here shows. 

Langevin helped create the residential schools and his writings on First Nations and Inuit are racist. It's not something to be proud of, the people most affected are offended and it's an easy win to remove his name from the PMO office.

First Nations and Inuit in these lands had their own culture, language, religious beliefs, successes and failures in life. Colonizing forces (here represented by Langevin) did what they do the world over - steal resources, denigrate the people and either annihilate them with force quickly or slowly assimilate them to death -often both.

It's hardly surprising that the descendants of oppression would want redress and sadly, not surprising either that many of the benefactors of oppression feel somehow slighted by a name change of a man most likely had no reason to respect in the first place.