Why now? The "bankable" FS is just around the corner...a matter of weeks away. Would not the BFS perhaps give a little lift to the stock price. Why not announce a PP after the bankable results are our.
Given all we know about La Balsa: excellent infrastrucure, immediate access to a year round open deep water port, proven pounds in the ground, and from the "prelim" FS, we know a substantical amount about how to process the ore and around how much that would cost.
A reasonably positive BFS, should give a bit of lift to Bell. Why not announce your PP after that...particularly as it only a matter of weeks away.