IanTurner - 11:59 am on Oct 1, 2012 (gmt 0)
I happen to know that Nominet works hard on trying to keep the reputation of .co.uk high and actively works with the UK police in order to shut down the knock off suppliers.
I'm not sure if Nominet ever chases money - their problem is more about how not to make money, as they are a not for profit organisation.
There are similar consequences to blocking your country code tld from outside registrants. For instance would Google own google.co.uk and Apple own apple.co.uk if foreign corporations were prevented from registering a .co.uk? There would just be a different collection of domain squatting UK citizens doing the scamming.