When I went to university in the 90's, Scheme was used in a couple of early courses. I had already learned C and Java on my own, but greatly enjoyed how Scheme made me think about problems differently. (I didn't learn Python until much later when I was out of school.)
As long as students are exposed to multiple languages, I think starting w/Python is fine. Every language has its issues.
> I'm not so sure someone who's good with Scheme will be bad with Python or Java.
They won't be. But students don't understand that, they want to learn marketable skills and are 18 years old. They haven't figured out that if your skills transcend language choice you will be more marketable even if it means you have to spend a few weeks learning a new language for a new job. They lack maturity, which isn't surprising given their age and experience, and so they complain.
On the contrary, I suspect that such a person is likely to be better suited to build software in either of the latter two.
I also suspect that Python is not a particularly good first language for someone who aims for a professional career building software.