Posted: May 16, 2018 12:26 am
I imagine Thanos believes the gauntlet gives him alone power over the stones but I believe the stones are independent, near sentient creations and thus, like the Ring from LOTR, can choose to act against Thanos or serve a more "worthy" owner.
Again, the scene where Thanos reaches out his gauntlet at Rogers and Rogers grabs the glove with all stones and prevents Thanos from moving that hand look at Thanos' face. He is shocked and confused as to why Roger's is able to hold the gauntlet. It is why he resorts to punching him with his other hand instead of blasting him with all stones.
Of course, I could be completely wrong. But it makes sense if the stones are very much capable of sentience and choosing who they serve. Think Age of Ultron and Vision's ability to lift Mjolnir due to the Mind Stone. I think that kind of theme will snake its way into the sequel.