Have you not heard of SLAPP lawsuits? The whole point of them is to make the defendant wrack up high costs, even in case where the claimant knows they aren't going to win.
It is incredibly naive to say the devs know more about bitcoin than CSW, so it will be easy for them to win. I'm sure they can hand their legal team pages and pages of hard evidence of CSW's lies, forgeries, technical incompetence, and so on, but the legal team will still be charging hundreds (if not thousands) of dollars an hour to go through it all to generate a winning case, not to mention the trial itself can drag out over several weeks.
a case is not won by who has the bigger purse.
Except often it is. A side which is clearly wrong (CSW) will have a harder time defending itself, but a side which is clearly wrong with a multi-million dollar legal team can easily beat someone who is right with no funding. And even if it isn't, CSW doesn't care about winning. He cares about intimidating people with these frivolous lawsuits and the cost of defending them.