The EU and US have made serious mistakes in the process but it's hard to disagree with that conclusion. Either you have a fairly short(By necessity, since Ukraine is going to remain crossable with armor for maybe a couple more weeks before the entire country turns into a giant bog in spring) proxy war in Ukraine that kills a few thousand and transfers the territory from one bickering cabal of oligarchs to another or you risk global nuclear war with boots-on-the-ground intervention. Putin has been pretty clear that he'll use nukes in the event of a full NATO intervention.