My issue is not with the results of the study, but with interpretation. I think it's possible to explain the desire to free the other rat purely in selfish terms without any nods to altruistic or empathic behavior.
Reproduction is for gene survival. We are simply throw away machines our genes have developed in order to propagate themselves.
The source code (genes) propagation per se would be completely useless to the system, without the processes they express: living systems, the most efficient energy transforming machines the system has been able to incrementally arrange up so far starting out of random stuff.
Therefore reproduction is exactly for that, for allowing the continuation of this energy transforming processes (life processes) in the most efficient way.