So what will providing proof accomplish anyway?
I don't agree. Something is better than nothing, even if things are heavily redacted. I as a common man may not interprete them adequately but there are people who can. Especially people from the intelligece community can check and somewhat verify if there is anything plausible with respect to the accusitions. This important for the allies of the Canada too. Canada is a member five eyes, so they can definitely validate their gathered intels with the likes of UK, US if the evidence deemed unfit for public release. So far I have not seen any of those countries conclusively made statements that they validated Canada's allegations. The investigation is ongoing anyway.
It does not matter whether Indian PM admits it or not if evidence is there and the international community verified and largely accepts it as truth. So far I haven't seen this happen.
Off course Canada can do whatever they choose in their jurisdiction. For example, many countries creates travel advisory for their citizens regarding which countries are deemed safe / not safe for them to travel to. If country X says that country Y is unsafe for their citizens to travel to, it's perfectly fine. However, that doesn't mean country Y is universally unsafe. But, when it comes to international relations we can't just hurl allegation to another sovereign country without any evidence, independent verification / backing. Because tomorrow country Z can allege something outrageous about country A without evidence, will the international community accept that without questions as well?
Personally I feel diplomacy from both sides have failed us. It's their job to handle these things more gracefully.