Well, yes and no.
Folks do call it a thistle; it is kind of 'thistley'; but it is really different from what I know as a thistle.
I am so NOT the authority on these types of things...but the internet says
Eryngium is in the family Apiaceae, which is the hollow stem family of carrots, parsley, and celery--whereas the vast majority of thistles are in that big, fat family Asteraceae, which is all those things with composite flowers like asters, daisies, sunflowers, dandelions, and thistles