You might view it as cherry picking (even though it's not the only line in the memo written with a condescending tone), but to me it is a big clue that the memo was not written in good faith to solicit discussion, but rather to push a pre-conceived agenda. As one of the interviewees says in the original article:
There’s a difference between “let’s have a discussion” and “let me tell you what’s up, all you wrong people.”
there are plenty of left-leaning memos and examples that show similar tone towards right-leaning and/or conservative or libertarian thinking. That doesn't imply not being open to discussion so much as showing one's bias. There's definitely a matter of levels to one's opinion, experience and yes, some level of conflict.
When going into a situation where you've been at the back hand of such bias, specifically in a workplace, it's often hard not to show at least some condescension. Look at any number of public feminist actions and statements, for example.
There’s a difference between “let’s have a discussion” and “let me tell you what’s up, all you wrong people.”