Let's say he wires $20,000 to his bank in Canada from overseas. This amount of money will be reported to the authorities. Someone may come question him about it. When he does his income tax, he is supposed to report world-wide earnings. He can claim that he was just transferring money, not earning it, but Canada Revenue may investigate further and see that it is earnings, which they will then tax.
If he wires the money to you, the government will again be notified. They'll want to know where you got it, and Canada Revenue may treat it as earnings, which means you will be taxed on it. You could claim it was a gift, or that your uncle transferred it to you and it is not earnings, but the tax authorities probably won't believe it is a gift, and if you tell them your uncle transferred it to you, they will see that your uncle is trying to avoid tax.
If you really want to do it, take a bit less than $10,000 in cash with you, and then give it to your uncle when you arrive. He can then transfer a bit less than $10,000 to his own bank account in Canada. This gets him up to almost $20,000. If he wants to transfer more, he'll have to do get other 'mules' to carry it for him.