I can see the SGI machines. Those were top of the line things (though sort of more for rendering...). The macs seem weird. I still remember wondering if he meant svr3 or svr4.
I think it was more about Macs not being used for scientific applications much until the 2000s. Up until a bunch of programmers up and switched to MacBooks, Apples were more usually used by more artistic types. They were quite big for writing and art stuff, then, mostly, though pricey. And no separate monitors.
That came later as Windows became dominant but in the era Jurassic Park was written/filmed in, I think they were used for industrial and scientific uses as well.
Some of it was probably chosen to make it seem expensive. And back then, they were seen as probably the priciest computer the average American might have recognition of, while being somewhat exotic compared to the IBM and IBM knockoffs.