Arguing that evoluton outside "kinds" is impossible is not valid unless there is:
a) A definition of "kind" that does not entail that all evolution is within a "kind"
b) allow the identification of "kinds" so that we can tell if a particular example of evolution is "outside" of a "kind".
Without such a definition the assertion is simply unfalsifiable - we could conclusively prove universal common descent of all earthly life and still not have shown evolution outside a "kind".
Disallowing such arguments would only handicap creationists if creationists have to use rhetoric to make up for a lack of rational arguments. I do not think that you want to claim that that is the true state of affairs.