*New bike with new tires that are not scuffed in can increase the pucker factor on already high pucker roads.
*I have a bad tendency to turn in too soon on the entry to corners.
*I have another bad tendency to chop the throttle in corners if I feel my line is terrible.
Well all three of these things can be easily corrected.
Yeah I would never do a spirited mountain twisty ride on new tires until I get a couple hundred miles on them!

Your lucky you didn't go down.
Practicing a delayed apex corner entry angle with a firm counter-steer always seems to work best on those types of roads.
Chopping throttle off in mid-curve definitely is telling you your not at the right speed or your in too high of a gear on entering the curves....ie trying to keep up with lighter, faster, more nimble sportbikes.
NOTE: I've learned when following fast riders to not focus on them. I actually pretend they are not there, I don't watch their lines, I don't watch when they brake, I don't try to copy what they do...I try to read the road conditions, curves, entry points regardless of what they do and I let my peripheral vision pick up any hints from them (harsh braking, avoiding road debris...etc) and that's about it.
Trying to play catch the leader with faster riders is the never ending problem for guys and their machismo. I've succombed to it in the past but I hope I'm past all that now.
Also no matter how good of a rider you are...we all get rusty if we haven't ridden in a while. It happens to everyone.
*I think I would fit in better with the EOM crowd than the sportbike crowd.(I hope)
Being 50yrs is not old first off. Secondly trying to keep up with
good sportbike riders on agressive mountain roads is pretty much gonna be a loosing proposition for 99% of us on FJR's. So why even try?
A wise rider once told me when you ride on the street,dont ride over 80% leave yourself 20 to get out of trouble.
Well said and I agree. I do this exact same thing for myself mentally. I ride at about 75% of my ability and try to not go over that.
My days of pushing 95%-100% all the time is just dumb and dangerous. I can ride a nice, controlled, quick pace and maintain that all day long. I'd rather ride like that anymore.