the only legalese problem i can see is that it is generally assumed that the whole of the pike code is owned by IDA.
public domain grants you unlimited use, but it does not give you the right to claim that you actually own the code (and could thus prevent others from using it)
however, i believe that this is not the first time that other code is incorporated in this way, so i assume that this is accepted practice, and then it is just a matter of clearly documenting the origin and ownership.
greetings, martin.