That's false. It's evidence, but it isn't conclusive. Someone thought that the law suit was worth filing, and that could be because the law suit has a chance of succeeding. It could also be some other reason, and it could also fail even if completely good faith -- this is why the evidence is non-conclusive.

> Someone thought that the law suit was worth filing

No, someone thought that they could win a lawsuit.

We live in a highly litigious society. This happens all the time.

It's not _evidence_, it's _suspicion_, and it's asking it to be reviewed in a court of law.

By your logic, counter-lawsuits and especially the SLAPP suits are also evidence.