Agreed. I don't think Emma should be a LI at all. I know she's technically "of age" and everything, but she has the mental and emotional maturity of a pre-teen. The fact that she is still dreaming of somehow setting up MC and her mother so they can be a happy family is also evidence of that.
However....
I believe Jenny is going to be a "good" influence, for those that want Emma to be a LI, because she seems to exist for the purpose of getting Emma to look at MC like a hunky man in the house as opposed to a father figure.
I'm opposed to it, and I really hope that any Emma-mancing is written in a way that is entirely avoidable, because this is probably a game that I would abandon entirely if not, but it's been pretty apparent to me since Jenny's presence became more prevalent that she's going to be a vehicle for Emma to start wanting to/trying to blur the lines of the relationship she has with MC.