And those from the peoples and tribes and tongues and nations
No doubt, the two witnesses "sang" the song in Revelation 5:9-10. What infuriated the world (people and tribes and tongues and nations) is that they were guilty of the Messiah's blood, and that true believers would eventually reign. The world had gone along with the devil, were decieved, and had a gut feeling these two witnesses were RIGHT. The world couldn't accept that they had chosen incorrectly.
will look at their DEAD BODIES for three and a half days, and will not permit their DEAD BODIES to be laid in a tomb.
Maybe there was a fear (belief) that these two (or one of them) was the Messiah. Jesus in John 2:13-22 indicates that after three days the "temple would be raised again". If Jews only considered Jesus a prophet, then they (and the world) would want to watch this happen. Modern television will make this verse possible. At four days much decay sets in (John 11:38-39-44). The two witnesses are DEAD nearly four days!
The "unburied" act also was a reproach to Jews which left them open to scoffing and derision. The devil has always tried to make fools of God's chosen people, Psalm 79:1-7.