I think Ms van Gelder means 'practical' when she uses 'pragmatic' to heap praise upon Bernie Sanders. She's not the only writer/pundit to use 'pragmatic' as a synonym for 'practical'.
Now, I don't recall Sanders ever referring to himself as pragmatic. Clinton, however, has used it in reference to herself; which is probably accurate for her concerning some issues.
Pragmatism, and its modern derivatives, originated in the 19th century with the advent of analytic philosophy in USA at that time; 'pragmatic', though, had already been in use since the 17th century. So ... what's the beef?
Simply this: nobody has any misunderstandings about the various meanings of 'practical'. But, if I say that Trump's position concerning building a wall at the Mexican border is certainly pragmatic but just as certainly not practical, would I simply confuse you? Or, would you know that being truly pragmatic means you have no moral values other than what works for you?
So, here's a rhetorical question: is Bernie Sanders pragmatic or simply practical in all he does and says?