I don't disagree with this - but since property value is pretty much always going up - you could always be saying "it will be worth more later" and putting off the sale in perpetuity. At some point you have to say the timing is right and go forward.
Say they are sufficiently reigned in and in the end, only sell off say, 30% of the land to cover the costs of any new EAs, flood plain requirements, remediation and whatever shortfall the city may have after belt tightening ($400 million?) and get somewhere around $2 billion for that land. They still hold the remaining property worth billions more and can spread out the sale of those lands at a futher 10% per yer so the sale spans 8 years in total as the valu of the property is increased by the redevlopment itself. This spreads out the development timelines and creates a very large revenue stream for almost a decade that not only pushes portlands development further, but likely generates revenues that can be allocated to other large ticket infrastructure that everyone wants - like more WT completions, higher order transit expansion, etc...
It should not be done to articifically keep property taxes low, though. Those should increase at the rate of inflation at minimum - but I think as long as the right controls are put in place and the vision can be adjusted to the approval of a larger number of stakeholders, then why wait?