I guess you're not very interested in having secure encryption then, which is odd since gridcoin is built upon it. The whole point of the RC5 challenges is to ensure that cryptographic algorithms are secure. If someone can brute force any encryption algorithm in a reasonable time, especially in a distributed manner, then it is no longer useful.
So you might see it as a waste of energy, but it's actually demonstrating that the algorithm is secure.
And since it has no scientific merit, clearly the challenge hasn't been spawning research into the topic, like such http://ieeexplore.ieee.org/document/4380736/?reload=true
Except, we already know exactly how secure the algorithm is. The breaking of this code will effective yield a single data point on a known statistical distribution of the compute power (or time) required to decrypt the message.