Basic rungs of support come in at X (1565, October 2007's high), followed by Summer 2011's high at B (1360-1370) and the Sep 2011 closing low near C (1130). In this context, the next major comes high overhead at XA's 1.618% extension D near 2050.
This pattern features a compact PRZ of ~10 points that is beneficial for devising solid R-multiple trade setups, even while making the zone more susceptible to whipsaw/failure.
I'm familiar with the criterion you're citing whereby the Q2 2010 correction removes the Q3 2011 correction from consideration and agree on strict theoretical grounds; but in practice, BC is the indisputably dominant swing between A and D, and therefore merits preference. If the pattern as drawn did not meet all Butterfly measurement criteria I would say that choice is too arbitrary; but it does exactly. In my experience, a rigorous but realistic technical pragmatism like this is of far more value than marginally useful hyper-precisionist promulgations discarding any pattern that doesn't satisfy draconian criteria set according to some Platonic archetype of pristine harmonic logical puzzles.
The issue that arises here is this. It is one thing to state "the B-C leg must be a higher low than the A-B leg with no prior lower low" as axiomatic. Like I mentioned, in theory I agree without giving it a second thought. But "prior lows" occur on a continuum. In fact, lower lows are happening all the time in an up-leg, at some level - it's the amplitude they install in an uptrend; and then the significance we attribute to their amplitude that have bearing on whether we decide a potential bearish 5-point pattern is rendered invalid.
Now one could take this to an absurd level and appeal to a 5 minute chart; but lower lows on the daily or weekly when drawing on a monthly definitely merit consideration; and they will be present on leg AB of almost any monthly bearish harmonic pattern. So, where do you draw the line of validity? (see chart; which low scuttles the emergent harmonic pattern?) There's no objective "valid" here - only what has tested best under a specific battery of criteria But this makes the "countless tests" done more than a little facile despite their supposed empirical heft, and encourages an unhealthy over-reliance in traders newer to harmonics, especially. Over-reliance is a far better place to start from than under, certainly.
The guidelines are hugely important; but in my experience - contrary to yours, it seems - they can be too onerous, especially when they've been elaborated under the aegis of someone such as Carney, who it seems is intent on eliminating as much discretion as possible. Countless hours of study and observation create their own competency and intuition that isn't always in strict harmony with the rules. Ultimately, as you say: to each their own. It comes down to whatever works.