Here a part of the script i just went to fetch quickly showing that Lucca does reprogram.

Marle
What?!
It might attack us!

Lucca
I'll make sure it won't.*
Machines aren't capable of evil...
... humans make them that way.**

Marle
Lucca, you... pity them, don't you?

Lucca
Let me get to work now, okay?

*She will make him not be able to. Isnt that a proof ?
**They judge based on what they are programed to do. This isnt a will of his own.