I don't back a man that took showers with his teenage daughter....
If true at all, then that is YOUR personal opinion - so up to you
FYI, around 15% of Europeans participate in Free Body Culture (FKK) - aka fully naked at lakes, beaches, Saunas and restricted areas for FKK members. For you unbearable - for them, simply natural - and yes they also shower naked alone or with family members at home who are also into FKK.
Now if one of them happens to be a President and the other person is his daughter - so what??
Did he molest her? did he try to make sexual advances? did he force himself into her shower? did she refuse her father to take a shower with her?
Since you don't know, it's simply your puritanical mindset - that automatically envisions sexual motivation or acts - aka You're SICK.
Which BTW your choice of language already proves more then enough.
On my part - I find FKK strange, but if people like it, I just let them be, however FKK culture is not matching my Character/mentality.
But what I find totally sick are people who in a civilized country with a working and reliable law and order system - walking around in public with a handgun or a Semi-auto rifle and referencing the 2nd Amendment, whilst posing as an imminent danger to everyone else.
And don't worry I probably own more handguns, semi-auto weapons then you - keeping them locked at home or taking them to the shooting-club/range or to military and local enforcement installations.