The link quotes "Jim Powell, co-inventor of the bullet train and current director of
Maglev 2000", who is a great authority.
So for more context, in reference to the originally proposed California segment:
"Powell has tried out the same route for a possible "bullet train"-style maglev track, and says the the increased speed makes turns extremely difficult. At high speeds, even a gentle turn pulls passengers to the side. If the loop turns too sharply, the force will make passengers sick.
Powell's research finds that passengers can withstand about a tenth of a G in lateral force before causing problems. At 600 mph, that gives the Hyperloop a turning radius of 40 miles. That’s an extremely straight line, and it means the project will likely have to travel through some populated areas."
What he's talking about is a (valid and relevant) comfort issue, at the top speed. Yes, for the longest segment at the highest speed, you would want the straightest route. But near end-points, at slower speeds tighter turn radii are possible.
Hyperloops
can turn. Saying they can't is like saying Amtrak trains can't turn. For tighter turns, they slow down. Because of their slower speeds, and physical limitations their routes will generally allow for more and tighter turns than a hyperloop should have, but much wider turns than that of a Smartcar. It's all relative. Different modes of transportation are often more appropriate for different situations and applications than others. It's situational (as others have mentioned above).
(And sorry for my typo. A's = as. I wasn't smart enough to proof-read what my smart phone produced.)