well i talked with leo bonard and this is what he told me
"Its purpose is to provide RFI grounding for anything that is in contact with a metal ring around the hole.* E.g. if the heatsink had metal standoffs than C567 would provide grounding to the heatsink itself.* Very nicely thought out engineering but...
You've guessed it, standoffs are plastic! So, Rob, you are lucky, just ignore it! "
So its all good .