Very interesting. I am not very familiar with this viewpoint and looked for a refresher/ overview, sure there may be other resources: https://christinprophecy.org/articles/the-pre-wrath-rapture/ My understanding has always been pre-trib rapture and witnesses left on earth during tribulation and new comers to faith in Christ during tribulation. I believe that could explain the beheaded coming to judgement(they came to faith and died during trib) and those waiting in heaven are the pre-trib raptured waiting until the 7 yr tribulation is finished and they ride from the heavens behind Jesus to destroy the world and all evil. Ill go look up scripture to backup and edit. Edit : The Seventh Trumpet: Revelation 10:7, 11:15, 18 “But in the days when the seventh angel is about to sound his trumpet, the mystery of God will be accomplished, just as he announced to his servants the prophets. . . . The seventh angel sounded his trumpet, and there were loud voices in Heaven, which said: ‘The kingdom of the world has become the kingdom of our Lord and of his Christ, and he will reign for ever and ever. . . .’ The nations were angry; and your wrath has come. THE TIME HAS COME FOR JUDGING [AVENGING THE BLOOD OF] THE DEAD [MARTYRS], AND FOR REWARDING YOUR SERVANTS THE PROPHETS AND YOUR SAINTS AND THOSE WHO REVERENCE YOUR NAME, BOTH SMALL AND GREAT – AND FOR DESTROYING THOSE WHO DESTROY THE EARTH.”

Source:https://wake-up.org/144000/the-144000.html

Before the Great Tribulation begins, God will select, empower, and seal 144,000 servants who will serve Him as prophets during the Great Tribulation. These people will speak for God. Because of religious arrogance and gross ignorance, most of these servants of God will suffer the fate of prophets in ages past. (Matthew 23:37)