A quick update. I have had another response from Lifemiles and got the same reply:
"In response to your request, we would like to inform you that flight availability is subject to the conditions established by our airline partners. They are the ones who determine the airports authorized for mileage redemption, based on their own operational and logistical policies. We thank you for your understanding and remain attentive to assist you in whatever you need."
Just have to wait, I guess.