I did a little bit of research and Google'd around, some ppl do mention specific morphs as displaying more "aggro" than others, Mojave came up a lot in search results, but it's mostly mixed response judging from what ppl have written; some agree certain morphs /are/ more defensive or harder to handle, and some ppl say it has nothing to do with the morph, and rather, the /line/ the snake comes from/has been bred from.
I was just so intrigued by this rumor because I had never heard of it before or encountered when I first started doing research on bp's and after I got Solidus and started to interact more with local bp owners, "morph aggression" has come up often.