I'm still not clear on what you mean by volatility. Take this morning for example. My PP is down 0.13%, due to gold and TLT being down and the stock portion being up. So the volatile swing in gold is attenuated by a rising stock market, and overall the PP is right now less than 1/4 as volatile as a 100% stock and higher than a 60/40 (which is currently about a 0.1% move up)
You are saying that on days when assets are correlated, that each asset class might be up or down in tandem, say 1% and that makes the GB more volatile?
If I've got 5 GB assets each at 20% all moving 1%, the entire portfolio moves 1% And if I was in a 100% VTI setup instead, that move would be 1%. Same for a 60/40 TLT/VTI.
And the same results for a negative move.
So on days when all assets track, it doesn't matter what your allocations are, everyone gets the same move.
I suspect it all comes back to you not liking holding gold because that is a wildcard that doesn't fit into any "normal" portfolio.