If anywhere, in RIPE NCC, physical presence should not be viewed as a number one priority. Even a 'company-sponsored' chair can be denied travel by employer or have other business to take care of during the meeting week. If physical presence is an issue, I propose we fix that problem, not accept and then enforce limitations.
This is tricky. It's not possible (or at the least 'very challenging') to chair a working group session at a RIPE meeting without being present. Having said that, not all co-chairs need to be present at each and every meeting. Speaking as a former co-chair of a WG, I know of instances of co-chairs being absent from a number of WG meetings, whether it was through other commitments, having recently become a parent, or just a clash within the meeting. However, habitual absence does force the work onto the other chairs. If Denis believes he is going to be able to attend future meetings, then I don't see that is an issue here. Rob