As a lead, I cannot designate somebody to call SEA. Once the flight is on a maintenance delay...it's pretty much out of my/our hands. We can only follow what we are being told by the maintenance staff or the pilots. We were told the plan was the plane would be leaving on or near 530PM.
Even with that 530PM delay, if Southwest had seats....we would have placed passengers there. But they didn't....Jetblue didn't have seats to LGB either. AA was an option, but they also had a cancellation on a SNA flight, so everything was full on them. We even looked for any possible flight to do a flag stop. That means if there is a plane traveling from SEA-SNA or something else to the LA basin, and there is open seats, we'd ask if they could make an additional stop in OAK to pick up passengers. There wasn't even that.
Regarding management not being there or being there, that is something I don't want to get into on a public forum. Either way, I think the outcome would be the same.