It's a shame that someone of your obvious intelligence posted this.
http://www.seiyaku.com/customs/crosses/peter.html says that:
"Peter is believed to have been crucified upside down at his own request, as he did not feel worthy to die the same way as Jesus. Therefore many Christian sects use this cross as a symbol of humility.
He was an early missionary in Asia Minor and the Roman Empire and founded the Church of Rome with Paul, Emperor Nero saw this new church as a threat, and began a campaign to eradicate these troublemakers. Peter was imprisoned, tortured and finally crucified. Such was his faith, it is believed, he remarkably succeeded in persuading his sadistic captors to change from the normal way of executing prisoners. Apostle Andrew also was crucified, and he too requested that a cross different to Christ's Latin Cross be used. Therefore we have another cross form, the 'X' shaped St. Andrew's Cross.
In 1920, Archbishop Joachim of Nizhny Novgorod was also crucified upside down, on the Royal Doors of the Cathedral in Sevastopol, a Black Sea port of southern Ukraine.
Sometimes this cross is called Satan's Cross because it points downward to Hell. But this is a misnomer; Satan was never crucified on a cross, rather he fell to his death1. This inverted cross is sometimes used by Satanists to mock the Latin Cross and its meaning."
Step back a little. There is more to Heaven and Earth...
That is pure myth. Everyone was crucified the same way no matter who he was. One might just as well reason that the one who wanted to be crucified upside down just wanted to be different, to stand out from the others who were crucified normally. So rather than a symbol of humility it might be construed as a symbol of pride.
A gruesome death by suffocation occurs in a normal cricifixion, but how does one die upside down? Wouldn't he pass out first.
BTW Thanks for the link with all those crosses --- amazing. Every religious order and group had their own distinctive cross --- obviously a lot of cross-breeding going on in the church at that time --- but very few upside down crosses.