Does this mean that every preacher who has ever expounded on a Bible story and added the least bit of conjecture as to motivation or thoughts or words is potentially guilty of falsehood and under a curse? Does this mean that to avoid even the possibility of falsehood and being under a curse, no preacher should ever do more than read the Bible to their hearers and leave it at that without comment?
Should any and all artwork used to teach children Bible stories be banned? After all, we do not have photographs or videos from thousands of years ago to prove that the art is completely accurate. The artist is taking license with the Bible description to guess what they think it looks like. What if the images, paintings, and drawings of Jesus and his disciples, of Noah, of David and Goliath, etc. are NOT 100% accurate? Does this mean children are being taught falsehood? Every time a Sunday School teacher goes beyond reading the Bible and tries to tell the story in their own words to make it easier for kids to understand, does this put them under a curse if they mess up a single thought or word?
This seems to me to be a brutally legalistic standard (based on a single proof text from Revelation) that is not followed in common practice among any Christians I have ever encountered. As a practical matter, all believers allow some amount of leeway in interpretation and explanation of scripture. I have yet to ever see any preacher or teacher only read the Bible and then for fear of being under a curse leave it at that. At some point, all of them enter the realm of conjecture of "I think this is what the Bible says in this passage" (whether they admit it or not). Of course, there's a wide range of opinion about how much leeway is okay.
Personally, I have no issue with well researched and well written fiction. In the case of a story about Judas, my criteria would be this. Has the author done a lot of research on the geography, climate, politics, economics, society, etc. of 1st century Judea and Galilee to present it accurately? Is the author representing 1st century people accurately as 1st century people or merely dropping 21st century people from the US or Europe (with their values and outlooks) into the story? Does the author clearly paint a picture reflecting the different scholarly opinions about Judas' motivation and leave the reader with the same uncertainty we have today about why Judas did what he did? If so, this is not all that different than a good sermon or research book on the topic except presented in a way that some people (who might never read a history book or Bible dictionary or theological treatise) might enjoy and learn from. To the extent such a work is faithful to Bible accounts and accepted scholarly research, it could be a useful teaching tool. To the extent it is wild flights of fantasy to push a particular opinion, it is not a useful teaching tool anymore than a poorly done sermon or poorly researched history book is.