I think there is a middle position here. Geno may or may not know if he has a roster spot. He also may not know with certainty if there could be potentially more than one available, and he may or may not be able to predict with much confidence what Sarah will do.
Of course he knows way more than we do, but if there is still some uncertainty, then recruiting for every potential possibility is prudent. That doesn't necessarily mean he knows he has a spot, just because he is still actively recruiting someone. Sometimes a coach has to keep recruiting for plan B and plan C. In essence contingent interest and potential offers depending on how many roster spots do become available, and what decisions other high priority prospects make.
If he truly has an interest in Chen, and it appears that he does, then it still could be contingent on several other things happening first, or perhaps he knows that two openings will be there (yes I know the math) and he can use one on a big (Sarah or portal) and one on Chen.
As long as some uncertainty remains here, you can't assume Geno knows he has a roster spot for everyone he is still recruiting. He has to cover all the bases until the pieces start to fall in place.