Some underlying messages you can take away from what Mccallum said:

1) He is pleading with China not to ratchet up the tension and leave Canada with no room to manoeuvre.

2) The Canadian government does not believe American having a case against Meng given the political and extra-territorial nature of the indictment. Of course, the Liberal government would prefer a court  to shoot down the US request. In that way, they can say to both the US and China that Canada has an independent legal system and the government will not interfere in the process.

3) If the court fails to do so, the Liberal government will quash the extradition request...You can count on it. Of course, they would prefer #2. And this will create a lot of problems with the US but they will do it.

However, they will throw the US a bone. So Huawei's bid to provide 5G in Canada is DEAD regardless what happens (#2 or #3).