1) We are prying into Water's claim regarding the redirect, hence the votes to get Water to full claim. He hasn't responded, so I don't understand the point of targeting Speed now beyond simply challenging his understanding of one or two roles. He clearly didn't fully understand how a Bus Driver would work at first, and quite honestly, I've never dealt with a Redirector before myself, so I wouldn't be surprised if this was Speed's first time encountering it. Maybe that's sus, but I can't decide whether to be suspicious of Speed or Water at this stage without getting more information.
2) If this is the sole basis for pushing a lynch on Speed, it's pretty weak. They almost certainly are not scum partners because there wouldn't have been a disagreement in their stories if that was true. That would be incredibly sloppy scum play from Speed. The first scenario you provided sounds a hell of a lot more likely because Pie was consistently on Speed for a lynch in DP1 and led the charge throughout it. He would have to have assumed that Pie was either scum or vig, but even if neither of those were true, the reads in DP1 were thin at best. He made do with the information he had, and this was one of the most prominent pieces of information that round.
3) We have actionable information. That doesn't mean we could not use more. You keep dismissing the importance of character claims (pointing out one instance where a focus on character claims failed to result in a town victory is pretty weak reasoning - the information isn't what cost us that game), but treat a lapse in understanding of a rarely used role as sufficiently suspicious to pursue a lynch?
4) In general, your whole argument is for why you're not claiming doesn't make sense to me. You don't think character claims do anything, but despite their pointlessness, you'd sooner be lynched than provide your own. Maybe you think your particular character claim would be too obvious. Maybe you think character claims are only useful to mafia. Maybe you're just standing on principle and don't want to engage in what you see as a pointless practice. It's probably the last of those based on what you've been saying so far, but I wouldn't be surprised to see that position change in later DPs when it becomes safer to make a plausible fake claim. Alternatively, maybe you'll just keep holding out and claiming that there's always something more interesting to focus on. Whatever the reason, I'm just incredulous of your argument that these are simultaneously pointless and that keeping yours to yourself is entirely worth being lynched over.