Two ways to look at it i guess. My thoughts were around scarcity. If demand for shares will increase with positive drill results (which i guess we all believe in otherwise why hold), then the less shares in the float (ie not held by MIN) the more valuable each of those share that are likely to be.
Also like you said, "as MIN increase their ownership of NWE, their position is strengthened and conversely minority NWE holders are weakened". And this only increases as more are sold - which means IMO as each is converted, the value of the remaining shares increases.
I also hold both. I hold to make money.
NWE Price at posting:
6.1¢ Sentiment: Buy Disclosure: Held