Also if it takes the proxy settings from apt.conf it's not dependent of environmental settings of the root account, it can use these proxy settings to contact the ppa and use gpg with "--keyserver-options http-proxy=value".
Also if it takes the proxy settings from apt.conf it's not dependent of environmental settings of the root account, it can use these proxy settings to contact the ppa and use gpg with "--keyserver- options http-proxy=value".