I would find that the up and down variation we see in species would be good evidence that such changes cannot accumulate.
To claim this you have to ignore a huge amount of evidence for transitionals, as well as laboratory experiments that show speciation.
That evidence shows speciation happened and that it is not just an assumption. That evidence also shows that the claim of no speciation, based on the biblical "kinds," is false.
No adequate mechanism has been ever proposed by creationists to show that speciation cannot take place after a certain number of changes have occurred. That there is such an (unknown) mechanism is an (unsupported) assumption based on religious belief rather than scientific evidence.
Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.