"Let's focus on the worthwhile parts of what he's saying" is a silencing technique used against those who complain of sexism.
Specifically, if someone's message contains some sexism, or someone's behaviour is sometimes sexist, people are exhorted to focus on what is worthwhile in their message, or the positive aspects of their behaviour, and ignore the sexism.
Since very very few people are continually sexist and sexism is often not the only content in a message (although online a lot of trolling can be content-free sexism, so it does happen), this leaves complainants unable to object to the majority of sexist speech and behaviour.
It also gives people a "get out of jail free" way to be sexist, in that they learn that as long as they do not stoop to content-free sexism, they can be very abusive and people will still work with any apparently productive aspects of their behaviour. Additionally, it means that geek community leadership almost never has to take the step of excluding anyone, if they insist on only excluding people who are 100% sexist and never anything else or in any way useful contributors.
Instead of being ignored, sexist content or conduct should be treated with at least as much serious consideration as a factual, typographical, or grammatical error.
