I wouldn't sour this batch for three reasons:
1. As others say, you can probably dry hop and still have great beer.
2. Commercial lacto cultures from White Labs and Wyeast are pretty weak. Meaning, they don't do well even at moderate IBUs.
3. Bitterness can be really difficult to balance with sour. So even if it's moderately bitter it might be better as something like a pale ale than a sour.