Use the OnCenter instead. It's very nice.
You need a big open area on the floor for all the grads to sit. The On Center certainly has that.
How big the the crowd for Commencement these days? I vaguely remember the crowd from when I graduated all those decades ago. It was in the Dome and I think it was in the 10K range. Maybe more. You would think most grads will have at least 2 people attending as guests. Some with a lot of friends or family could have considerably more.
Does the On Center even have permanent seating?
I would think the amphitheater could be a little problematic with grad seating. They would sit under the roof and probably take up all those seats. How many grads does SU typically have? 3K? Maybe more?
The crowd would probably have to sit on the lawn. This facility at least has the video screens and sound system so the crowd can hear and see the speakers.
The biggest downside is the lack of a roof for the crowd.
Assuming we need a venue that holds at least 10K, what other options are there nearby?
The Landmark is surely too small. As in the Civic Center. Maybe the War Memorial is large enough. I know it is used for HS graduations.
CNS is outdoors and probably too small. The AAA stadium has the capacity but would require putting a lot of seating on the field in the middle of the baseball season. Even if they used playwood or other temporary flooring, I would think the Mets would be against it. Probably not a viable option.
I think it comes down to the War Memorial, if it is big enough, or the amphitheatre.