Exactly. The provision already exists when both spouses are 65 and over and both receive the guaranteed income supplement. There is a provision already in the Old Age Security Act that allows the benefits to be calculated at the single rate based on their own income, which generates higher GIS benefits, but as you mention, in the case of couples when one spouse is younger and between the age of 60 to 64 and thus entitled to the allowance, the same provision doesn't exist. The amendment wants to just mirror the provision that already exists for these other couples.
On November 17th, 2016. See this statement in context.