No big conspiracy. The event needed vests to provide quick identification so that the right people can get into the right areas. Since Sony is a sponsor and probably agreed to supply the vests for free (not uncommon), it is not surprising that they are wearing vests with Sony on it. Paid advertisement.
Just like back in the late 90's when Canon was a major sponsor, everyone was "forced" to wear Canon adverts.
It is all about advertisement and who pays for the vests/shirts.
I support several NPO events and I am "forced" to wear all sorts of advertisement but have never been even asked what camera system I am using or not using. \
Beats paying my own money for a shirt/vest.