No, they don't just use the software because it "feels familiar". Everyone is acting in their best interests, nobody is going to sit in a sub-optimal position just because they can't be bothered. If you use non-standard software, then everyone else will reject your proposed blocks.
The only way you can use the concept of Schelling point is to explain why so many people use Bitcoin rather than Litecoin or another slightly-tweaked variant. Much like the example in the article, if you ask anyone to pick a cryptocurrency to pay with, they are likely to say Bitcoin because it is familiar.
When people choose to meet at Central Station it is also in their interest - this is the same mechanism. It is a case where it is beneficial for people to choose the same thing - and people choose something because they believe others will choose it as well.
Yes, that makes sense when you're talking about why a person would choose to transact with Bitcoin. It's not "invalid" to choose Litecoin, it's just more familiar and easier to use Bitcoin. Schelling point is about social familiarity.
The reason people avoid invalid blocks is because they would have to convince every other node out there to accept it. It's a coordination issue.
The only way you can use the concept of Schelling point is to explain why so many people use Bitcoin rather than Litecoin or another slightly-tweaked variant. Much like the example in the article, if you ask anyone to pick a cryptocurrency to pay with, they are likely to say Bitcoin because it is familiar.