I know how the ST business model looks like - they want to popularise thei board to earn money later.
Assuming that the espruino is targetted at hobbists market the ST, TI, freescale are great choice (cheap, feature-rich), etc.
Maybe releasing espruino for as many boards as possible is a nice choice.
Speciall features could be licenced to get some money from it (it's clear for me that you need money).
Since Kickstart success the popularity of the espruino rised somewhat, I guess.
But I think the main barrier is the espruino board itself.
I personally have about 20 different boards from many vendors (most of the subsidized) and I am looking for for common development environment.
I would look for opportunity how to popularize the espruino-javascipt among hobbits but I would not limit it to a single board (the mentioned "Unsupported board" headline might be discouraging).
I am sorry for these words - you know I have been a fun of the espruino since the beginning.