Having said all that, we should remember what is the Supreme Law of the Land.  Most people in the United States will say it is the Constitution, but of course they will be wrong.  Tax treaties can overrule the Constitution.  And we have a tax treaty with Canada.  Of course there is some debate about whether tax treaties are "real" treaties that permit the Constitution to be ignored.  

Article 22 of the US-Canada tax treaty says, 

"Items of income of a resident of a Contracting State, wherever arising, not dealt with in the foregoing Articles of this Convention shall be taxable only in that State, except that if such income arises in the other Contracting State it may also be taxed in that other State."

So does that apply to unemployment compensation?  That would mean your question isn't about the $10,200 exclusion, but an exemption of the total amount even if more than that.  

There's an interesting Tax Court case from 2017, in which IRS argued that unemploymnent was indeed "other income" under Article 22, when it involved a Canadian collecting U.S. unemployment. 

https://www.parkertaxpublishing.com/public/tax-treaty-canada.html