FWIW, the TMA made a chart back in the summer that listed travel by plane as moderate-high risk. It's level 7 on a scale of 1-9, along with activities like getting your hair cut or eating indoors at a restaurant. This is based on TMA physicians expert opinion.
They then released an updated holiday version of activities by risk level, which had travel by plane as level 5 on a scale of 1-10, which falls under moderate risk. It seems like they have downgraded the risk of plane travel, but the holiday chart also lists a lot of holiday themed activities, which I'm not sure how many people are doing those anyways.
Furthermore, JAMA published this information in October that says "the risk of contracting COVID-19 during air travel is low".
https://jamanetwork.com/journals/jama/fullarticle/2771435
Obviously, travel increases risk of contracting or transmitting COVID because you are inevitably exposed to other people. At the same time, there many activities that are higher risk, some of which people are doing routinely without a second thought. Perhaps shopping in a grocery store, sending your kids to school, or visiting family during the holidays are all equal or higher risk.
Everyone's threshold for the level of risk they are willing to accept is different. I personally feel that travel can be done in a relatively safe manner if you plan carefully and take steps to mitigate your risk. The airports are half empty and the planes are clean with everyone wearing masks.
If someone wants to shame me and others for feeling that way, I can sort of understand that position but I would also be curious what activities that person had been engaged in during the past 10 months. I would suspect that 80% of people are in some way engaging in activities with equal or higher risk at times.