This article is from 2010. These days the TSA is using millimeter wave scanners (with frequencies around 30 GHz).
In fact, the ones in jails have you stand on a 5-sec slow-moving conveyor belt as you pass through the x-rays, giving thousands of innocent people awaiting bail (among others) a much greater dose than the airports were giving.
There is no opt-out for these people.
The millimeter wave machines are less dangerous, but they also don't really work well at all and have a high false positive rate. They're pretty much security theater, which we're seeing a lot of again now.
Would those be the same group of people who are "concerned" about 5G towers today? You can always find a small group of people who are "concerned" about anything you like. The press uses this for nearly every such story they publish. Without statistics quantifying that "a lot" the statement is meaningless. And even if you have the statistics, there being "a lot" of them is not a guarantee that they were right. One would need to present evidence for their concern as well to be treated seriously. Such evidence does not exist, since airplane flights themselves are a source of radiation exposure.
https://cdn.vox-cdn.com/thumbor/DZqWhneDEMxElDzz7ZiUk0Jv93w=...
I worry a lot more about eating hamburgers than anything less than 100 mSv.
I assume this chart is still good to show to people: https://xkcd.com/radiation/?
Yeah I still love this chart!
X-rays are very much different from the sub-100 GHz bands used for 5G, and the concerns raised at the time about backscatter xray scanners were that the safety of the systems had not been demonstrated sufficiently to start irradiating everyone who got on a plane, because the negative health effects of ionizing radiation are well understood.