We are not simply waiting for the passage of time for Hyperia to reopen.
We are waiting for a change in circumstances, things - potentially a large number of things - need to happen, need to go right, to trigger a reopening. Nobody knows when those things will slot into place. Not Thorpe, not Mack, not the Sun, not TS...nobody.
Therefore the closure is totally indefinite. It's closed until it isn't, and there is no date currently set for that.
Yes, testing is a positive sign, but in terms of reopening, it tells us nothing if we don't know how much testing is planned, what's actually being tested, and how things will look if testing shows that the fix isn't satisfactory, or brings up other problems. Similarly, a date in T&C's doesn't reveal anything if we don't know what the T&C's look like after that date.
I hate the Sun with a passion, but they're doing more of a public service regarding Hyperia's closure than Thorpe are managing. Already Thorpe have had to apologise for using language that made the closure appear to not be indefinite.
At this moment in time, and for the past few weeks, there is not a single visit date you could choose, from now until the sun swallows the earth, that will be within the known operating dates of Hyperia. Because it's dates of operation...are entirely unknown.