I personally think that the only reason a junior explorer would...

I personally think that the only reason a junior explorer would stop exploring was when it has found something of value and does not want to risk losing it. Shifting focus to a new project means taking another punt at a big unknown. You might lose the bird in hand while trying to catch another.
Regarding the Cobalt market not recovering soon... I'm not so sure about that. This market is dominated by Glencore, yet Cobalt makes up just a small fraction of Glencore's income. The result is Glencore has the ability turn on/off the "taps" as they like, with almost no impact to their cashflow. It is a lesson in monopoly and diversification.
So, unless I'm way off the mark and Glencore is somehow a charity organisation in disguise giving away free Cobalt, the price recovery of Cobalt is guaranteed. My bet is it will go close to USD$50k/t before end of this year, as the consumers try to stockpile again.