Good that you got some knowledge from the cook.
Not being there and not actually tasting...my impressions from you report (if you'll indulge me):
"I still think I pulled it too early..."
and
"The thicker the slice, the more chew that is required."
I'd likely agree: Perhaps too early. Imo, though, this has to do with the foiling delay. If you wish, try next time to foil around the 2.25-hour mark or so. Don't bother temping--just foil. Provided your cook temps next time are close to the same temps as you cooked this time there will be no issue there.
Even cooking is more likely to be achieved--as well--by foiling earlier than you did. No big deal--just saying. You could do the same thing as I mentioned above--tuck some foil under the thin end of the roast. Though it didn't look like (in your pic) the end was receiving much direct heat it is certainly possible. The extended unfoiled time was likely a factor.
Regardless, it seems to me like you got much closer to what you are looking for--and that's the name of the game. And, further, your meal looked great.