Even though I'm not a woman, I still have a general idea of what it's like.
The examples are not contradictory. Blaziken is saying that, if you are not part of the oppressed group, you have to be aware of your lack of firsthand experience.
You don't need first-hand experience to understand solutions or empathise with someone that has been oppressed. If you don't have first-hand experience, you need to be aware that you need to do much more listening than you do talking and you shouldn't argue with someone of that group about their experiences .
You would need first-hand experience to say "I know what that's like" otherwise you don't really know. You have not lived their experience.
"I know what it's like" is a dangerous statement, anyway, because it is so vague. What part do you know? How I live my life with the impending threat of harassment or discrimination? Or do you just understand that I have to face it every day?
Note: Bold statements are quotes.