Of course we don't want the DF to be the Center for Missing Inmates, but it seems like a more natural avenue for some characters to take than making a panic-inducing network post. It's just an option!
Neil would probably notice Lacus wasn't there, but I'm thinking his first thought would be "let me look for her; maybe she's off somewhere and isn't wearing her communicator" rather than jumping on the network in a panic within the first few hours. I'm married and I probably wouldn't panic until the next morning came (but my husband and I aren't attached at the hip, so... yeah).