I think reasonable people can disagree on this. Fruit of the poisoned tree doctrines eliminate bad incentives for law enforcement to commit crimes in their investigations. But when doctrines such as this cause the guilty to go free, it erodes public confidence in the rule of law. Like many things, its a tradeoff - and the legal system is a process of discovery and adaptation, not some simplistic set of unchangeable rules. Justice for one must always be upheld. I think this ruling is pretty good at threading the line here.