Possible to "lock" BuddyPress xprofile fields?

Perhaps this isn't the right forum to ask this question, since it's not directly related to a WPMUdev theme or plug-in, but it's worth a shot...

I would like to "lock" an xprofile field, so users cannot change their response once they have completed the registration process. Do you know if it is possible to make an xprofile field "non-editable"?

By way of example, on our site -- http://www.generation-europe.eu/summit2010/register/ -- we would like to "lock" the question where members agree to abide by the rules.

There is a discussion thread on the BuddyPress site about this issue, where I have already asked for more information (username: GEF), but there hasn't been a response in 4+ weeks:

When I look at the "_bp_xprofile_fields" table in the WordPress database, I see there is a "can_delete" value, but that doesn't seem to "lock" the field.