There's an explanation here
, written by the same guy. He actually does suggest 'signatures of virtual reality' there, but I think fails to ask why they would be necessary unless the next universe up was exactly the same, in which case it would be a simulation too, and so on.
If that sounds crazy to you — well, you could be right. It is certainly possible to overstate mathematical links between different systems: as the physicist Eugene Wigner pointed out in 1960, just because a piece of mathematics is ubiquitous and appears in the description of several distinct systems does not necessarily mean that those systems are related to each other. The number pi, after all, occurs in the measurement of circles as well as in the measurement of population distributions. This does not mean that populations are related to circles.
Yet for a moment, let us imagine that this alternative Matrix-style world contains some theoretical physicists, and that one of them asks, "How could we discover whether we live inside a Matrix?". One answer might be "Try to detect the presence of codes in the laws that describe physics."