When I am emotionally invested in the outcome of the conversation? Nope. I wouldn't say anything unless it was brought up by someone not me, and then it would be flipping a coin as to whether or not I chimed in.
However, there are a lot of things I simply don't care about*... That no worries, I'll dive right in. As long as I wave myself in the general direction of tact (like not bringing something up in front of bosses or kids and T.H.I.N.K. before you speak: is it true, helpful, inspirational, necessary, or kind?).
So, for me, it would depend on how much I cared about the topic, and my mood in that moment.
___________
1. Care about = am invested in the outcome of the conversation, or there are repercussions to myself -or others- that I'm not willing to risk.
2. Don't care about = not invested in the outcome of the conversation, and regardless of whether the person dives in and we talk for hours, or blows me off, or gets really upset at my speaking to them... I'm affected not at all. I'm solid. Basement rock boundaries. Whether I'm (a) currently struggling, or (b) long past having any issue with either the subject matter or talking about it.
Ex1) I've spent 15+'years hiding PTSD. Oy vey. What actually got me here was a guy I know offhandedly disclosing about his combatPTSD. He didn't even know I served, much less anything else (although I've been a little wild around the eyes, or wearing my sociopath hat on more than off, so who knows. Maybe he tells everyone, maybe he was reaching out. I have no idea). The one offhand remark left me looney. Because the past 2 years I've been back to square 1. Bad. I desperately needed/wanted to talk to him about it. But I couldn't bring it up. I was waaaay to emotionally invested in the outcome of that conversation! Which is what led me here.
Ex2a) I struggle with the downsides of ADHD an awful lot sometimes, but am also very solid about it.
Ex2b) Rape, meanwhile, the only way I could care less on a personal level is if it didn't exist. I can do the 20hr ER schlep with someone who is acute, be trading coping mechanisms with someone months or years out like baseball cards, or be talking about it academically/abstractly until the cows come home. It just doesn't affect me unless it's day in day out. Ugh.