I wasn't referring to transmission on the plane. I was referring to the fact that international travel for purposes of tourism, etc. is a privilege, not a right

I wasn't referring to transmission on the plane. I was referring to the fact that international travel for purposes of tourism, etc. is a privilege, not a right. No country is obligated to allow in foreign nationals who are at a higher risk of serious illness if they get infected. This especially makes sense for poorer countries that are already under pandemic strain. Furthermore, border controls can be effective at limiting the introduction of variants. When countries do choose to let foreign nationals in, at this stage of the pandemic, it's not unreasonable for them to limit arrivals to those with immunity, whether vaccine-based or natural, or apply different requirements (such as quarantine) for people with immunity versus without.