Not sure there is much value in that argument, it was a short term tenant before the sale (though the reasons why it was only a short term deal are not clear, perhaps that could be expanded upon)
Why did the council commission Strutt and Parker to value the lease on the 250 year basis if they were only ever selling it to Wasps for its original term?
I don't think they're saying otherwise are they? They are saying that the whole deal was contingent on the lease extension, the council arguing otherwise is disingenuous in the extreme though on the face of it what they have done isn't illegal.
You're comparing apples with pears. SISU's argument was that ACL on a 40 odd year lease was worthless and would have struggled to raise the finance on the open market. It's a different proposition to ACL with Wasps and a 250 year lease.
How wasn't it a penalty!? Laughable. The only point worth making is that the ref or lino should not have missed such a stonewall penalty in the first place.