I don't think so.
I think you misunderstood the words he said to Tashigi, in which I suppose he intended "don't accept blindly other people's ideas of justice, but make your own".Regarding him, the case-by-case justice is NOT a proper idea of justice, storywise it wouldn't make him interesting.
Until now we saw him addressing what he clearly saw as the "major evil", Crocodile or CC immediately pose a threat that was way bigger than the threat Luffy would have posed.
Though imho it is too much to label him as the "case-by-case justice" guy.
well smoker is the one who always say "a pirate is always a pirate",while instead he made the strawhats escape after they managed to escape from the rain dinners,and didn't scold tashigi for ltting the strawhats go at the end of the alabasta saga.
also,he is the one who in the end stayed at the "party" after the punk hazard saga talking calmly with law.
he is hardly someone who doesn't change his mind,or someone who could be taken as a champion of coherence.
and hionestly,i was not saying it in a negative way,justice is not something that it is absolute,so relying on your judgement on a case-by-case base seems incredibly smart from my point of view