Just because Rory knew their baby Melody became River didn't mean he knew the whole story. Hell, he barely knew any of it other than the Doctor and River, in their world, met in the wrong order. The Doctor's future was River's past. They had a journal to keep things in sync so they knew where they were. And River feared the day that the Doctor no longer knew who she was.
Rory knew he could look up his daughter's life online. Find out about it there. But he'd rather hear it from the source. So when Amy mentioned to him on the network under a filter that River was going to talk about her past, Rory knew he needed to be there. Life in the medbay was finally settling into a bit of normalcy with Martha Jones appearing and Rory was grateful they had two reliable doctors that were able to be there. And the Metacrisis Doctor had helped immensely too.
Maybe I'll buy some biscuits to bring tomorrow and a bunch of tea... he thought as he slid into the TARDIS and made a beeline for his and Amy's room. He clutched the box of tea he had gone out for in his hands (it was Amy's favorite) and he soon pushed opened the door and his eyes fell on his wife. Setting the tea to the side he moved immediately to her and pulled her into his arms and held her before kissing her by way of greeting and saying hello.