I wonder if it's a case of they feel they have to open. I think everyone understands its closure last year, but if they still have the contract and still pay money for it, and Covid restrictions aren't disappearing any time soon, I guess they have to bite the bullet eventually. If the interest it generates from being open ultimately makes them more money through merch sales than the money they spend on staff and running it, I guess it's a good thing. Though I imagine it's a risk as to whether it actually will...
I'm sure the cynic could suggest Thorpe are opening it to show to the higher ups within Merlin how ridiculous the ride is and they need money to either complete re-imagine it or replace it. But who knows.
Walking Dead is an interesting one. Storm Surge requires a minimum of 4 people in a boat, so groups of 3 or less we turned away last year. So it wouldn't be much different to that. Obviously it's a bigger problem since it's a bigger ride, but there is form there.
Of course, there isn't actually anything stopping the park from sitting people from different groups next to each other. Whilst the idea of social distancing is very much engrained in our minds as a society at this point, the recommendation is - to the best of my knowledge - keep 2m away from people, and if you cannot, wear a mask. That's why mask wearing has been so important in indoor spaces, such as shops, where it is impossible to stay 2m away from people at all times.
And this kind of circles back to the points that were raised when parks were first re-opening: what use is social distancing on rides really? When you hurtling round a coaster, what difference does it make if a stranger is sat a row in front of you or next to you? Don't get me wrong, I get why it's being done by parks, and in the absence of any scientific evidence, it's probably the easiest thing to do to keep people feeling safer and happier, but it is very much a placebo-like thing to do.
For reference: when I was at Parc Asterix last year, they were completely filling up trains. No social distancing, grouping people together and even using single rider queues. Admittedly it felt a bit odd at first, but really, I didn't feel any less safe compared to the UK parks with their socially distanced trains.
Anyways, I've rambled...I imagine Thorpe will go with the easiest rule of 'only even-numbered groups can ride', unless they've someone managed to change the 2 person per row rule (which I doubt)