GeertJohan hasn't posted for months, no one has confirmed he has quit the coin.
Just ask him he's on the Guldencoin IRC all the time https://webchat.freenode.net/?channels=guldencoin
but not respons
That's just a wild guess, that's impossible to know if your aren't in the channel.
Geert is in the transition of changing jobs, he will be moving over to his new company at the start of September. He has to handover his current workload to new person so has been under pressure and working late nights. He is still very much part of the guldencoin team and will be more active again from September on wards. Geert is still maintaining all services that he has developed for the coin.