Shining one:
What do you mean by old earth creationist? And what theory of evolution do you mean when you say "evolution".
I think that since all the animals in the world today could not fit on the ark anyone who claims to be a Christian must accept that life evolves if they also believe that the flood account is real. In fact they would have to believe that life evolves even faster that scientists do because the Flood would have occured not that long ago. Or else they would have to have some supernatural explanation that is their own interpretation and not in the Biblical account for how all these animals fit in that ship, the dimensions of which are in the Bible.
I don't think Creation, intelligent design or the various evolutionary theories constitute a polarized issue. It doesn't have to be one or the other. Not all naturalists exclude the supernatural and not all creationists exclude that life can evolve.
I don't think the Bible prohibits life evolving. If I understand right it states that God made life in its basic forms and then life reproduced according to its kind. This leaves open that life can evolve after being created. It is also extremely lacking in any details of how all this creating happened. I wouldn't get too dogmatic about the process. I don't think the account was meant to be a reference book in any way. Maybe even allegory.