How important for you is it to do this particular summer e-course in geometry? I have heard of some schools requiring 95% or above in each quarter to get into a honors math course for summer. Those schools are reputed to be "rigorous", whatever that may mean.
The 98% cutoff seems to be a little on the high side - as if they want kids who score consistently A+ in their math and science tests. If that were the case, why not look at other options available for summer honors geometry courses? There are various math enrichment centers offering them and you can find some locally depending on where you live. AOPS has a geometry online course that runs through summer as well.
If your son finishes geometry on his own through other resources, you can ask the school if he can test out of geometry and be placed in Alg II for 8th.
