There are two important quotes I would like to point out from that paper:
It is certainly clear that hand washing can reduce the risk of infections (39). However, the deposition of potentially pathogenic bacteria on the hands after hand washing to remove transient floras reduces the effectiveness of hand washing
Note the wording: “reduces effectiveness” means you should still do it, it is still effective, just less so.
These results did not differ significantly from those for bacterial colonies deposited by hand dryers from the same bathrooms when calculations of the colonies deposited by hand dryers and small fans were corrected for the times for air exposure and rates of airflow from these two sources
In other words: moving the air around is the cause, so a bathroom with paper towels that also has an air conditioner or fan will produce similar results. You know what else moves air around similar to a small fan? You when walking around, your hands are moving air and contacting lots of it.
I could reply with a study that finds air dryers to be safer and filter more bacteria, and we could go back and forth until one of us grows tired. Instead I’ll leave you with a review of several papers published on the matter where you can see that it’s not so clear cut, there is discussion around it and it doesn’t help that the vast majority of papers out there are financed by either paper companies or air drying companies (btw, kudos for citing one of the independently financed studies)
https://academic.oup.com/jambio/article/130/1/25/6726080
If you don’t want to read this, the long story short is that we don’t have enough evidence to conclude whether they are more or less hygienic:
The second question we sought to answer is ‘Are PT safer than hand dryers relative to human infection risks?’ We found no data to support any human health claims relative to hand dryers vs PT use.
And finally I leave you with another quote from this paper:
Of notable importance is the need to evaluate risks from hand‐drying activities in consideration of handwashing scenarios, given that the greatest uncertainty in hand contamination is associated with the handwashing method, and not the drying method.
In short: not washing your hands is worse than any drying method.
