Nope, not making this up.
Have a look at relevant documents regarding OGP crew requirements (e.g. GS ES LSO 131).
Having done several audits with OGP auditors, they always were looking for crews fulfilling their requirements.
While they were always happy to have two "Commanders" fly on one helicopter, they were also clear on the use of Copilots in their dedicated seats, stating that a copilot-before being allowed to fly "right hand seat" needs to be close to being upgraded to Commander.........
If things work differently in the North Sea-great, good for you.....
I will stick to my opinion that a "commander" is not an "instructor"-hence should not "train" someone (unless authorized to do so by Company procedures, e.g. as Line Training Captain).