Like I said, the castle messages appear after you've decided whether to save or not, regardless if it is a normal star, a castle star, a 100-coin star, or a bowser red coin star. If the game doesn't ask you to save, the message won't appear. But it will appear the next time the game asks you to save, including for in-level stars!
I think there's also a message for star 120 so if the death star glitch can be done for that one in a way that wastes less time than the combined time of {landing, giving the
peace V sign, zooming out, coin counting and mustache brushing, and saying don't save} then that would be a neat way to save time in the 120 star run. But that won't happen because the 120th star pretty much has to be BitS red coins.
Also if you can do it 2 times in a row for the first 2 collected stars, you can skip the 1-star message.
Oherwise, the death star glitch is a neat trick that might save time, but it won't save you from castle messages except what I wrote above.
EDIT: yeah CoolKirby, it's the V sign, but since they are both the same gesture with a meaning that depends on context, and Mario is probably using it because that's what Japanese people do when posing, in part thanks to peace activism... or maybe just declaring victory... whatever :P
So your movement is waaay more optimized than my crappy attempt ( from -18 to +22 means you did Spiral Mountain 30 frames faster), but you didn't start as quickly as possible. :/