Rose kept a lot of secrets so she likely kept the secret that she didn’t shatter pink in order to protect her finds, and so if they did get captured by the HG they wouldn’t say a word. It could once again fit into rose being evil as she kept vital information that would’ve helped the cg and hg and didn’t.
This is also a highly romanticized, biased account of somebody who is made up of a gem that’s single minded and one that doesn’t care about the present. So this is likely how garnet thinks it went down, or this is how rose told her.
My theory is that either A) all the diamonds collaborated and rose just happened to be at the wrong place at the wrong time or B) pink faked her death and her and her pearl are on another planet, maybe even the jungle moon, and rose just took the blame because it’d help her cause.