I think Weidman just watched the Rocky IV movie where at the end all the Sovietic people were standing and clapping Rocky and he thinks that something like that may actually happen in real life.
Another theory is that probably Weidman watched Fedor vs Coleman II or Fedor vs Sylvia, where despite that they were fighitng in th USA, most of the people were cheering for Fedor, and he is hoping that the same will happen with him.
What he fail to realize is:
1) Anderson does not has any minimal interest in fighting him
2) If the fight happens, all Brazilian fans will chant "You will die" to Weidman, and they will be very happy when Anderson finishes him.