The only question is whether Watsi and BCBS operate within similar enough markets for their use to be considered infringement - I'm less sure of that.

Even if they're in different markets, Blue Cross is well-known enough that they may also have a colorable "dilution" claim.

Bottom line, if you're a startup and you get sued, you've already lost. Good on them for not wasting time fighting this too hard and getting on with their work.