Would you toss em??

[greymule]

From your description, the umpire should have ejected the runner when he apparently deliberately spiked the fielder.

Your question is akin to, "A police officer sees a man shoot his next-door neighbor and warns the man not to do it again. If the man then kicks over his neighbor's garbage can, should the officer then arrest the man?"

As an umpire, I would never tell a player that he didn't need to slide. A player can slide on any play, even into 1B on a routine grounder where he's out by 10 feet. How he slides is another story.