I basically think this is correct and it comes down to lawyers. It's now the team of Trello lawyers, AND the team of ACME company lawyers, against Sole Person

I basically think this is correct and it comes down to lawyers. It's now the team of Trello lawyers, AND the team of ACME company lawyers, against Sole Person and their lawyers. From Trello's perspective, that is much more of a winnable battle then Trello V Person V ACME. If you're likely to be sued by the loser on the side of a battle, get sued by the one with a smaller warchest.