That could be applied to making any law. We're talking about a specific law. This specific law lets Canada transition to endemic Covid, where there is enough community immunity that its public health system isn't overwhelmed and rationed. Without it, Canadians either have to wait through prolonged mitigations until community immunity is built up naturally or Paxlovid supply becomes sufficient, suffering the economic consequences of those mitigations, or rip the mitigation band-aid off and let care be rationed (and divert taxes to pay for all the hospitalizations) until natural immunity takes care of the problem. If my worst political enemy likewise justified their policies in my interest, I would happily let them implement those policies. If my best political friend did not justify a policy in my interest, I would oppose it. Each policy should be evaluated on its merits.

Your appraisal is an example of the slippery slope fallacy. The only slippery slope is encouraging people to evaluate policies by who is proposing them rather than whether the policy is beneficial. Then the person who is proposing policy can get away with policies that are more and more in their interest and less in mine. As long as the standard of evaluating policy by whether it is beneficial is upheld, there is no slippery slope.