Just using a counterfeit chip could potentially introduce unintended behavior. I've dealt with a number of USB to serial chips and many of them are crap. I have cables that will just suddenly stop working, or the baudrates that suddenly change. I wouldn't be surprised if the counterfeit chips have similar problems. FTDI should be able to program their chip and expect it to work as designed. If it's counterfeit and it doesn't, then it's not their fault. They shouldn't have to debug problems in counterfeit chips. On top of that, the counterfeit chips eat into their bottom line. FTDI chips tend to be more expensive and for good reason. They're better chips. On top of that they have excellent documentation as well as library support for doing all sorts of things. Want to do i2c or JTAG with their USB to serial chips? It's fully documented with a library to support it.
I can tell you as someone who writes device drivers that trying to debug problems caused by some unknown counterfeit chip is a nightmare. After all, it's not your job to Q/A not only your own hardware, but cheap Chinese counterfeit chips as well.
As far as I can tell, sending an ASCII string is probably the best thing they could have done given that they're screwed no matter what they do.