I VERY strongly disagree.
Take a look at the 1984 numbers (5 Spanish medals). The most heavily doped countries (Soviet Union and East Germany) did not participate. Yet Spain got fewer than 1/4 of the medals that Spain got 8 years later in Barcelona when there was no boycott..
You include the obvious protection that Spanish authorities have been giving it's dopers, and Spain's success in sports that Spain has traditionally done poorly (like swimming, where Spain has poor facilities, and poor development programs), and it is clear to me that the pendulum has swung the other way (from Spain being at a disadvantage to now where I strongly believe that Spain's results are heavily inflated).
Here is Rafael Munoz (world 50m butterfly recordholder). He has smashed the records of previous swimmers who were probably doping themselves.
By the way, Rafael missed three out of competition tests in 2010 (although he was "acquitted", because he was emotionally upset).