You are important, I can prove it

Sam had never encountered anything like this before, no... he hadn't even thought about it.

From the first dream initiated by Mia, Sam had always been somewhat prepared, but the preparations from the real world couldn't be brought into the dream, so the only thing that was effective was his mental resilience.

This was perhaps the only thing that might be somewhat useful in this place that existed outside the real world.

Sam had thought about how he should respond if such a situation occurred again.

Should he pretend to be deceived and just go with the flow?

Or should he confront it directly and expose the other party's true nature?

Sam chose the latter.

Because going with the flow, you never know what outcome you might end up with. Since he felt that the Mia in this dream wasn't the real Mia, then he shouldn't expect things to develop as he hoped—it was an impossibility.