One thing worth noting is That Sokaku stressed that daito ryu (or the inner "oshiki uchi" techniques at any event) were essentially defensive in nature and should not be used offensively...
Yes, and the Sagawa scroll suggests the same sentiment.
Like Chris said, if we go at face value, the idea of "being peaceful" goes back to Takeda or before. I guess the thing to wonder is: is this all just words that budo people are "supposed" to say? In some circles you have to recite the party line to be seen as legit.
As I said, I personally tend to think the whole DR lineage is indeed an effort to produce a budo that is guided by the desire for an end to violence. But there is plenty of room for argument there. For instance, what are the kakete techniques doing in the Takumakai if the art is for defence only? I think it is explainable (especially at the 1:10 ratio that Mori cites) but it does muddy the waters.