WalkinMan said:
1. Locutus/Picard was not assimilated in typical fashion, because he was to be a 'speaker' of sorts and 'not just another mindless drone' which is how direct assimilation may have worked. They wanted to keep his individuality more intact so they assimilated him slowly.
In First Contact, we see assimilated (by nanoprobes) ex-Enterprise crew waiting to have arms, eyes etc cut off and replaced with implants.
So nanoprobes only Borgify a person (grey skin, removal of hair, merging with the Collective). They then need to be Borgified with attachments.
Also in FC we saw at least one crewman being assimilated who KNEW he was being assimilated. He said, "Captain...please..." and Picard shot him to spare him full assimilation.
So it is entirely possible that the scene in BoBW where Picard sheds a tear is a combination of invasion by the nanoprobes and a physical addition.