There is the possibility due to a lack of consensus on what “consent” means across different first nations. This proposed amendment is in relation to the application of standards to ensure that there's safe drinking water and waste-water services on first nation lands and the choice of those standards. Should all of those discussions need to happen individually with different definitions of consent, it could slow down the application of those standards.
I'd also point to clause 6 that was already looked at in terms of paragraph 6(2)(a), which allows for first nation law-making. First nation laws could always make a different choice at any time as well.