Er, no. I suspect that it's an option that very few people would have any use for, since one of the main virtues of Multitrack mode is that you can split tracks into clips, slide them around and group them - selectively. Generally locking takes place after this has happened, and not before!
If you are actually talking about locking tracks at the time they are created then I have to agree with SteveG but if you actually mean to have an option to have recorded clips locked as they are recorded then I would have to agree that this would be essential
And before anyone asks - it makes sense because that is the point on the timeline that you are recording so clearly that is the point in time that you want the clip to be (at least for the moment)