Hey, I'd like to challenge your view about advice to "learn people skills" which seems to push responsibility to one group, those who aren't already people skilled enough.
There are more extroverts than introverts in the world. The first group is happy with social contact, talking with people and generally score better in empathy. Introverts are the other way around: they prefer to use text, do not like to give in to emotions and score worse in people skills. That's according to the book "Quiet: The Power of Introverts" but I guess it's not a controversial point to make anyway, and while you can find many outliers as in any discipline, I think it's a fairly good generalization.
Now, it may depend on the company or group, so two scenarios:
1) Introverts are a majority, extroverts a minority - maybe that's a tech company: shouldn't extroverts use their people skills and be able to figure out that introverts mean no harm and just prefer to communicate by sending long pieces of text with many scientific sources cited instead of talking with even one person? They might have even been doing this for many years, in the introvertive bubble of their fellow colleagues who shy away from emotions. Of course, extroverts could still feel emotionally touched and maybe even attacked as the minority - but then, been empathetic and knowing the style of introverts, shouldn't they try to teach them people skills? Are we sure firing this person is going to be an actual lesson to him? Or maybe there is no way to teach introverts people skills, as Google with a load of money and staff cannot even challenge beliefs of one employee? How come then we can ask single introverts to learn it on their own? Does it mean we're all doomed as more and more tech companies change from big groups of introverted engineers to cross-disciplinary team with a mix of characters?
2) Extroverts are a majority, introverts are a minority - again, using their people skills extroverts would surely recognize that introverts are not comfortable with people skills... so if introverts are a minority, is firing them for miss-following the code of conduct, written most likely by the majority i.e. extroverts, a form of discrimination? For the sake of diversity, shouldn't they all learn about more scientific, less emotional approach? Or should you be schooled only if you're in the minority without those skills?
IMO author of the memo made a decent attempt at using his people skills on this paper - what the post from Sabine acutally acknowledged, although you could generalize based on her background she's an introvert as well. It just looks like that other people have higher expectations of people skills but the question is have they done enough to learn the science skills themselves or just assume that everyone should have people skills at the exact level they want because they dictate so as a majority.
(Cheers, sorry for all the mistakes, English is not my native language.)