So
% Console Piracy is a lower percentage than the PC market for similar games, the total number stolen games is more on the Consoles due to a larger number of pirates. Of course the consoles are dedicated console devices, so you have 1M pirates, but you also have 30M+ non-pirate potential consumers.
I disagree with your math...
1. We only hear about modding users banned from Xbox Live. About 30% of Xboxes never get online, so any number of those could be pirates. The fact that they don't play online suggests that this group has a higher amount of modded consoles. Also, because they aren't interested in online services, there's a chance that if they mod the console then all of their games are pirated.
2. Those who go online with their modded consoles do it for the following reasons: access the marketplace content or play online. Both cases suggest that these users have perfectly legal games as well and do not use the modded system for pirated copies only.
The issue gets a little more complicated when you try to compare it to the PC. Usually pirated games are excluded from official online multiplayer gaming, so anyone interested in that will still have to buy the game (although there are pirated servers as well, and then there's LAN play*).
However, it's still possible to buy just a few games and pirate the rest as there's noone to ban the user from anywhere without any method of 'screening' their system. Steam might be an answer to his though, I haven't looked into it in years (even forgot my login) as my home system is far too slow for any PC gaming nowadays.
All in all, Joker's probably the most informed here, having seen actual statistics. And it really is just a question of small percentages, the magnitude of difference between the closed and open platforms is still clear.
* So ironically, whenever there's an online petition for LAN gaming nowadays, there's a good chance that a lot of the people signing them wouldn't buy the game anyway