I actually just learned that a few days ago. Check out biblos.com and the lexicon for Rev 7:9. It's a lot faster than flipping pages. Have your friend note the definition for "before" that the r book gives and then have him ask where the angels are in verse 11 when they bow down before the throne. It can mean in the sight of or in the presence or face of, but which makes more sense especially considering how the same word is used to describe so many other things in heaven: the lamps, the sea of glass, the 24 elders, the dragon is before the woman when she gives birth?
If your brother brings up the paradise hope, Rev 21 describes the new heaven and new earth with the Holy City of Jerusalem on earth after Satan is abyssed. The nations walk by its light and the kings of the earth bring their splendor into it. How can they do that if the city's still up on heaven? I don't know how your friend believes, but a lot of Christians believe in a heavenly hope and then a paradise where heaven and earth are one. It doesn't have to be one or the other, it's both.
It actually makes more sense when you consider that hope for a paradise earth or a seperate class with a different hope isn't mentioned by any of the apostles. Their hope was for heaven. I think there's one mention of a new earth in 1 Peter but that still doesn't contradict Rev 21.