Then 4G or Wifi may be worse than 5G. Experiments with inter-cellular adhesion were, among others, at 900MHz and 1800MHz, thus closer to 4G. However I don't know if other frequencies were really investigated (or with the same care, with different effects observed on male and female rodents, etc).
I appreciate that in your brief analysis you are considering several mechanisms of action besides just the heating. There may be many kinds of resonances, at molecular level, supra-molecular, etc. If very little 900/1800MHz suffices to alter BBB, then it is like a trigger to worse things, without the need of much energy. In the animals tested, the amount reaching the brain, at typical GSM levels, had already the observed result. Of course my tone is speculative here, but if the effect was confirmed in humans, it would not need much energy, and just the medium-to-weak signal reaching the brain could be worrisome.
There are not yet any studies on it, but if the effects of 5G on BBB were much stronger than with 900/1800MHz, it may also be the case that much lower signal intensities would still alter noticeably the BBB, even after the attenuation of the body traversal.
I am not a luddite at all, but I do hope that scientists working to certify that 5G is healthy are not hand-waving away the problem only by saying that the energy absorbed is too low or that the body is blocking its intensity. That would mean they did not hear at all about the effect of the mere frequency as a signal on the adhesion between cells.
I really would like to see some study elucidate the mechanism (or the absence thereof, and the flaws of the previous study), maybe some sort of resonance, soon enough to avoid to be in a situation were Wifi/4G/5G would be everywhere yet with dangerous long-term effects on health.