I would be more concerned with finding a drier place to store your car. I have had a lot of cars over the years and have experienced this only one time. That was years ago when I was in a pinch for storage, and stored my car in a dirt-floored barn that had water running through it. In retrospect, it probably would have been better stored outside where there was at least a little air circulation. In my current situation, I have the largest dehumidifier I could find and am able to keep the relative humidity in my storage unit at under 35%. I don't have any good reason, but I don't think blocking the clutch pedal down is a good idea.
As an aside, although I got the clutch unstuck, it needed to be replaced the next year. May have been a coincidence, but....