IINM, ISU regulations require Messing, as a representative of Canada, to travel to Sweden on his Canadian passport. Still, Messing trains in the United States, so this isn't really a problem. He can get back into the U.S. with his U.S. passport.
This can't possibly be true, as it would create situations that run afoul of the law. E.g., Imagine a dual U.S. and Belgian citizen who trained in Canada (which I believe Alice Sue Claeys was at one point). The ISU could not require her to enter the U.S. on a Belgian passport, or she would be arrested and jailed.
Similarly, a U.S. skater with dual European citizenship MUST enter the European Union on the EU passport. It is a serious offense, again subject to arrest and prosecution, if they enter their country of dual citizenship on the American passport. It's also technically illegal, though less likely to be caught, if they enter another EU country on the U.S. passport. It creates a potentially serious international conflict, should the person commit a crime or otherwise get in trouble, because the EU has "supremacy" while an EU citizen is in an EU country. The U.S. State Department has very limited rights and ability to help a dual American-EU citizen on EU soil.
Other countries have similar rules - I know of dual Australian - UK citizens who were detained and questioned for hours when they tried to enter Australia on their UK passport. The whole airport was shut down with alarms, etc. when they scanned their UK passports in the self-service machines.
The ISU may require skaters to present to competition officials a passport or ID of the country they're representing, but they cannot require skaters to travel on it. In Messing's case, it won't make a difference, but in other cases, it will.
Dual citizens, travelling between their two countries or a related country (in the case of EU/EEA), need to travel with both passports. Use Passport A to check in with the airline. Then use Passport B for exit checks. Then Use Passport A for entrance checks when you land. Then Use Passport B with the airline on the return flight home (remember to change the Advance Passenger Information). Then Use Passport A for exit checks. Then use Passport B for entrance. It seems shady and wrong, but it's the only legal way and will keep dual citizens out of trouble. Otherwise, you end up like my Australian-UK friends....
I suppose the "passport rule" is that when the country hosting the event sends out invitations to skaters who need visas e.g. somebody representing Uzbekistan in a skating competition gets an invitation accordingly. Not something he could present in inviting country's consulate in Russia with his Russian passport. Those who do not need visas can present what passport whey wish when crossing boarders.
Yes, this is right, subject to laws I mentioned above.
Isn’t this passport thing what caused Misha Ge huge issues because visas were harder to get with his Uzbekistan passport? He has other passports, but had to use that one for travel for skating comps.
What passport / citizenship does he have that's easier? Russian? Chinese? (I don't think China allows dual citizenship?) Neither of those seem much better than Uzbekistan, but maybe I'm wrong.