Dry yeast and yeast from a starter are in different metabolic states. Dry yeast has been processed in such a way that it has all the reserves it needs to grow and reproduce for several generations so you don't need to provide any oxygen when you pitch it. Once you make a starter you have taken it into the growth phase and used up most or all of those reserves so you will need to oxygenate or aerate your wort, just as for liquid yeast. You have wiped out one of the advantages of dry yeast, which is probably why it is not recommended. If you need to test the yeast, though, go ahead and do it.