A. Both of them were dictators that were arguably the scourges of their century. I'm going to assume that blazer isn't conspiring with Satan, the kool kids klub, &c, and is therefore not quite that bad.
B. Fair point.
C. It's generally assumed that your allies join in if you go to war, that's kind of why they're counted as allies. To pledge your support is a bit of a redundancy, and one that serves to inflame tensions.
I really do appreciate your show of support, but in this case, I'm asking you to be a bit quieter about it for the sake of diplomacy. If blazer's a better person than either Riddler or Stalin (assuming I meet such terms as well), diplomacy should play it part and render a military threat should be unnecessary, and maybe I'm a bit naive in thinking that blazer's not as bad as Riddler, but I'll take a gamble on it. Either way, it's my head in the crosshairs so if I'm wrong you can say you told me so when I go down guns blazing in a glorious final battle that will engross half the planet and likely end with New Manhattan being too weak to fend you off during your likely, maybe even inevitable, revenge attack.
Edit: There I go doing exactly what I asked Swat not to. :/