Well, granted I was not in Matos' head, so I really don't know what he was thinking or what his intention was in kicking the ref as in, I don't know what outcome he wanted to see.
Was he trying to kill him? If so he demonstrated an ineffective technique and gave TKD a bad rep.
Was he trying to KO him? If so he demonstrated an ineffective technique and gave TKD a bad rep.
Was he trying to miss him but make a point? If so he demonstrated an ineffective technique and gave TKD a bad rep.
Was he trying to split his lip to make a point? If so he demonstrated an excellent technique with great skill and control but still gave TKD a bad rep as it demonstrated a complete lack of self control violating one of the tenets of the art.
Other than Matos, nobody really knows what his intention was and therefore nobody can truly say if he kicked hard enough, used an appropriate weapon or chose an appropriate target. I do admit though that it is great fun to speculate.