The argument is very simplistic.
In biology we are dealing with more complex systems which are generated in a completely different way from the virus (i.e. the virus has no equivalent to developmental biology - interestingly Dawkin's biomorphs DO have a very simple analog to developmental processes)
Any experiment based on a single selective pressure is oversimplified. In real biology there are multiple selective pressures - and there is iteration (i.e. real evolution will offer a series of selective pressures).
To prove the point the argument either has to show that the proposed limits are inherent to any evolutionary process or that biological evolution shares the same limits. That means that it has to address the two points I raise above.
So, at present I cannot see why that the argument tells us anything useful about biological evolution.