It is my understanding that the blue-light-response reduces internode-length, counters etiolement, entices root growth and opens the cotyledons etc pp. So it's own effect influences the morphology as well, but if it directly opposed the Phytochrome signal-transducting chain, Id venture to say, rather not.
The blue is also associated with less leaf area, as a response to incr. heat stress, so this overall loss of photosynthates is just stiffling the growth promoting abilities of stable Pfr a little.