The article makes an assumption that if that loan is not paid back by then, the site would be sold for development.
That is probably not how it would work, and an alternative exists. The article says the loan enabled Atlas to meet an RFU deadline, without which their purchase would have fallen through, and they would have lost the half million deposit. They were between a rock and a hard place, and Holland knew that and was so 'nice' to make the loan to help them avoid that loss.
Really though, why did Holland make that loan? He must pretty much know that they can't repay him in 21 days. The article says to secure the right to play there for Wasps. Fair enough. But, to know that the loan would not get repaid and know therefore that even after making that loan they wouldn't be able to play there? He has Atlas over a big barrel right now.
21 days is long enough for the RFU to approve, or not, Wasps to play there. But short enough, and with that story having been hand fed to the Mail, that the RFU now thinks that they would lose to rugby what is a very nice stadium to become a shopping mall. Just how would that run in the press? It gives them little choice but to give Wasps the assent, and quickly.
Holland could then offer a longer term loan to pay off that short term loan, at pretty much whatever terms he wants. This is the tenant ruling the roost, and the landlord having no power at all. That simply does not happen in property development at all. Ever. Well, maybe sometimes. But, think about it, weird or what?
Holland cannot simply put the property on the market after 21 days. He would have to go to court, etc. So, not that soon. The loan could go in to default, where an administrator would be appointed, a sale quickly forced, at by now a really low value and Holland could acquire it (with backing from Wasps' new backers). And by low value, I mean really low, fire sale value. After all, who would want to buy a stadium and car park with little immediate potential for alternative use, and no potential tenant (Wasps being the only one in town)?
Looks like lost of twists and turns left to go. Did someone say a TV crew was following all this?