Look, you've got to use a little common sense, let's look at the facts, domaining is a legitimate multi million pound market if not billion taking in the wider scope of world trade.
A domain name has many uses and is used in many ways, if nominet are to now start judging how domains should be used perhaps they should only sell them to business and restrict sale, if you wish to restrict use then do so, otherwise do not get in the way of free trade or allow after the fact a domain in possession to be stolen from one registrant and passed on to another simply because a business or person has a different use or maybe no real use for the domain.
They have opened a contract with yourself, you neither asked nor requested that they use that domain in a certain manner so how can you justify leaving an open list of abusive or non abusive measures?
Reselling domains is legitimate, you certainly make enough money out of transfers, parking domains is legitimate, people type in domains of what they feel is right, there's a variety of reasons people get mixed up, firstly there's over 70 different world-wide extensions, mix up .com and you end up in another country, what are we proposing no parking where there's an issue a letter can be missed out?
As for registering domains, I hold over 800, what are my interests? Predominantly website development, secondly domaining and whatever I wish to with that asset while I hold the registration is entirely up to me, if I wish to park to get the most value out of that domain, I will, if I wish to operate a website or forward the domain then that is my right, if I wish to leave it dormant again, that is my right.
Is it someone's right to get the hump then I have the domain, of course, does that then entitle them to steal the domain and create untold paperwork in defending a DRS case, no of course not, individual cases should always be looked out, so yes, all above should be perceived fair use and not abusive.
Naturally, enough said, you've answered your own question, re read what you wrote.