When I was on the hiring team at work, I googled an applicant and discovered that they were arrested in the 90s for filming themself having sex with a cow. That is increadibly offputting but they had a clean record in the 30 years since then and even if they didn’t it was in no way applicable to the job in question so I simply disregarded that fact. Obviously I still knew they fucked a cow but I simply didn’t consiously factor it into the hiring decision. They did get the job btw.

I imagine it is the same for a jury. Obviously the jury can’t literally forget something that was said but they can consiously choose to disregard it when it comes to their final decision. Obviously it’s not perfect because any information admissable or otherwise will subconsciously influence someones verdict but if they try to actively ignore that info then it is better than nothing.