(And it's entirely possible that "too expensive" has just been a smoke screen).
I doubt it. SFTV has always been difficult to get or keep on the air because of the expense of creating it, especially if it's something ambitious with a lot of action or exotic settings/characters. That's been a perennial hurdle for decades, so there's no reason to doubt it's just as true here as it's always been.
I mean, let's compare it to its predecessors. BSG had its share of big action, but was mostly character-driven storytelling on standing sets and Earthlike locations, and most of its Cylons were just human actors. Caprica
had a lot of digital scenery to dress up Vancouver as Caprica City, but it too was mostly more down-to-earth drama, and it only had a few CGI Cylons, comparatively. But Blood and Chrome
, apparently, would be a full-fledged combat-driven series spread across many locations and chock-full of all-CGI Cylons all the time, and it's a cinch that would be costlier than the previous two series.