It's not a public vs private thing.

I've been in plenty of panel discussions where I have offered advice to female founders publicly. I was in a semi-open mentoring session just a few days ago when I did so. In fact, I've been called out in the pas for not being sensitive to women's perspectives. (No twitter mobs, thankfully)

Giving good feedback is a skill. Giving good feedback to people of different races, genders, ages, nationalities, etc is an important subset of that skill.

Perhaps i misunderstood the quantum of founders v coworkers etc - I assumed the latter would have been more frequent.d

Regardless, I do believe you aren't properly weighing the cost/benefit or risk/reward properly in public v private situations. One can have all the skills in the world, it isn't going to get the risk to zero. And if the reward is little, it doesn't add up for many folks.

I'm not a public person so I'm speculating.

I hope you're paid for it!