False. The English versions of B/W/B2/W2 feature no region lock. And before you point out "Those are DS games! DS games don't have region lock!", they are DSi-enhanced games and DSi-enhanced games usually feature region lock when played in a DSi/3DS.
It is possible to set the region in the rom itself. Take a look at your nearest B/W/B2/W2 cartridge, if you will.
My White 2 says TWL-IDRO-USA. The O means it's Region-free. Similarly, my White version says TWL-IRAO-USA.
The reason why the English versions are Region-free is because they wanted to save time by having the UK versions and the US versions identical, meaning they have the exact same rom inside them.
They had to make it region-free so that it would work on both NA and EU systems.
Proof:
https://www.youtube.com/watch?v=ex6phoub5_c
English White version, Japanese 3DS.
Now try playing a Japanese version of the Gen V games on a non-Japanese 3DS. Won't work because the cartridge is region-locked to Japan.
As I was saying, they have the language selection screen because they are actually using the exact same rom to release the game everywhere at the same time.