Whilst I doubt anyone is immune to the "argument from authority" fallacy I think it is most regularly deployed by the theistic side of the debate here at EvC.
How often do we see the religious views and opinions of eminent (or even not so eminent) scientists held up as justification for theistic conclusions of one sort or another? From abortion to cosmological constants via the very existence of a "designer".....
Whilst non-theists might cite the arguments of the likes of Stephen Hawking I haven't seen anyone say things along the lines of "Stephen Hawking is an atheist so there
must be something to atheism". Conversely there are many example of theists citing the fact that so-and-so believes the same as them as some sort of evidential justification for the belief held.