The reasons why Alton Towers is closing Blade and doing staggered openings is entirely different to why Thorpe Park have 5-6 rides closed. Of course, both are regrettable.
There are explanations for everything, as you have given. Of course, each explanation is perfectly plausible by itself. But that does not therefore make it acceptable that these rides are all closed. After all, rides are the sole reason Thorpe has guests!
There should be adequate buffer periods and time management built into the programme of work over winter so that the park is ready for opening day. Had there been 1 ride closed, I doubt anybody would be complaining too much - but 5-6 is pretty much unheard of at a major park (except Thorpe where, over the past decade, it has been quite common). There is obviously something not quite right about something within the management of the maintenance at TP.
If you don't blame Thorpe Park for ride closures, who on earth do you blame?