The lower room would not count as suitable house because it has gaps in its wall larger than 4 tiles. You can have as many gaps as you want in a room (even to the point where the room is more open air than walled as long none of the gaps are larger than 4 tiles large.
Thus the missing backwalls between the rooms is irrelelvant, as is the part with the missing wall on the upper room, each of these is only 2-3 tiles large. Where your platforms are located does not matter either, as you have them, they complete the room (and double as door).
The upper room should be valid (but sometimes the housing mechanic has issues with nonsquare rooms, try relocating the chair until it works), the lower one is not.