I passed here today, I can confirm the situation is still the same. There's also an F45b sign on Trassersweg when coming from Rue de Ransbeek, before the C3 with exception (before the service road to the right). There's also jersey barriers on the side of the road near where the C3 is. Will they be moved eventually to block the road? I can only guess.

IMO, a good approach here would be to map access based on the C3 sign with exception, i.e., `vehicle=no` + `horse=no` + `bicycle=yes`.