Jon, I don't think the velocity drop is something I would be concerned about because of the way viscosity is determined, unless they did the check useing the same temperature, opening in the test funnel and leavel of the oil checked that was used to determine the rated viscosity by who ever made the oil for Honda it would be different, besides the base weight didn't change just the winter rating which really isn't a big deal.
It would interesting to know where the heck lead come from but at least there wasn't a large metallic count which would indicate bearing brake down,,,,not good.
If there had been coolent in the oil the oil would have looked like Coffey with cream in it or in the early stages there would have been droplets on the dip stick.
For reasons beyond me as to why some oils will foam while others won't, I'm sure it's has something to do with the formulation of the oil, I do find it unusual that in today's market and advances in the oils that one would do that but in your case that's looks to be just what happened.
It will be interesting to see what your next oil will do, I personally have never noticed it in all the bikes i've owned with one exception, a Harley with the oil tank on the side of the bike, you coiuld see the returning oil and it would bubble quite a bit but that was a stright weight oil (50wt) and darn little tecknowledgey involved.