Is this normal practice or should we see something fishy here?
No, and yes.
He was given the offer Tuesday noon and asked to respond Friday morning
This is known as an 'exploding offer' and is always a red flag if the deadline provided is arbitrary*. In almost all cases, job negotiations don't have real deadlines, and the only purpose of this is to ...
I think 4 classes is plenty. I know people who only took one and got hired as Data Scientists right out of school.
Good on you for not putting up with that shitty place anymore, but I think you are underestimating yourself and the overestimating the degree of difficulty that Data Scientists have to deal with on an average job. There is a learning curve but ...
This is known as an exploding offer.
Follow the directions in the linked article to get rid of them.
https://haseebq.com/how-not-to-bomb-your-offer-negotiation/ (I'll come back here later to extract the relevant quotes, I just don't have much time right now)
But this is even far worse than an exploding offer.
Never accept a verbal offer by itself. A ...