At Revelation 7:9, the great crowd is not seen as being in heaven. Their “standing before the throne” of God does not require them to be in heaven. They are simply in the sight of God.
The WT certainly say this but they are even ignorant of the greek for 'standing' and 'before' or chose to ignore it. I suspect the latter.
Standing:
Revelation 7:9: ‘standing’ - the greek word here is hestōtes
Short Definition: I cause to stand, stand
The use of hestōtes in Revelation 7:9 is listed under Thayer’s II.1: ‘properly, a. followed by prepositions or adverbs of place
So the Great Crowd are standing before in a literal ‘proper’ sense,
Before:
The greek word here is enópios: in sight of, before
Short Definition: before the face of, in the presence of
Use of enopion in Rev 7:9.
How can the great crowd be stood in sight of the throne (where God is seated) and in sight of the Lamb (Jesus Christ - who is in heaven) and yet still be on Earth?
Use of enopion in Rev 7:11.
All the angels were standing around the throne and the elders and the four living creatures, and they fell facedown before the throne and worshipped God,
In this scripture, all the angels are standing and fall before the throne and worship God.
Are they on Earth or in Heaven?
Same words as Rev 7:9, but in a different location? How does that work?
Here are more examples of enopion (before):
Revelation 1:4 - "seven spirits that are before (enopion) his [God's] throne, ...."
Revelation 4:5 - "seven lamps of fire burning before (enopion) the throne [of God], ...."
Revelation 4:10 - "the twenty-four elders fall down before (enopion) the One seated upon the throne..., and they cast their crowns before (enopion) the throne, ...."
Revelation 5:8 - "And when he took the scroll, the four living creatures and the twenty-four elders fell down before (enopion) the Lamb, having each one a harp and golden bowls that were full of incense, and the means the prayers of the holy ones."
Revelation 8:3 - "And another angel arrived and stood at the altar, having ... incense ... to offer ... with the prayers of all the holy ones upon the golden altar that was before (enopion) the throne."
Revelation 9:13 - "And I heard one voice out of the horns of the golden altar that is before (enopion) God."
Revelation 11:16 – “And the twenty-four elders who were seated before (enopion) God ...."
So are all the above in heaven or on earth?
The great crowd are in naos (the divine habitation - where God resides) standing (literally) before (in sight of) the throne.
The great crowd is in heaven.