Getting back to the topic, most of the more recent crop of deserters were people who signed up for the pay and benefits offered by the US armed forces, but declined to carry out their part of the contract when they were activated or their units called up. Coming to Canada allows them to continue their parasitical lifestyle (get welfare or other benefits while in Canada), while not offering anything back. Taxpayers in both nations have a large enough burden without having to pay for even more freeloaders.
Regardless of our views of American foreign policy, military actions etc., this is essentially an issue between the American servicemember who knowingly signed a contract and the United States Government as the owner of the contract. (I make an exception for draftees, who did not voluntarily sign the contract). People who behave in this manner will offer nothing to our community; best to send them back ASAP.