From both these excerpts it is said that 17.5% or only (roughly) one in five Canadians are eligible for being prime minister or governor-general
If you are unwilling or unable to learn a second language, then you should probably seek another job than Prime Minister, since you will automatically alienate 20% of the population, making it difficult to actually do your job. For the record, former PMs Joe Clark, Stephen Harper, Kim Campbell and John Turner were not raised in bilingual households.
There is no requirement for the Governor-General to be bilingual. Traditionally, the post has been assigned alternatively to Anglo- and Francophones, but in recent years, we have enjoyed bilingual speakers as our head of state.