OK.....we all know you are a right wing Kool-Aid drinker and thinking objectively isn't exactly one of your strong points. So I'll explain it to you. I'll try to use single syllable words, as much as possible, so that this explanation does not go over your head. The United States of American. Is a constitutional Republic. In a constitutional Republic individuals (that's a big word which means "one man or one woman") have these things called "rights". One of those rights is the right to peacably assemble to petition the government for a redress of grievences.
Now this is where thinks get tricky for people, like you, who are cognitively challenged. Mr. Ryan is an employee of the Federal Government. He works for the people in the districi in which Mr. Nielsen lives. Now Mr. Nielsen has a constitutionally protected right to peaceably redress his representative in the Government for a redress of grievences, in this case, the social entitlement programs that he had paid hin entire life into, in which Mr. Ryan wants to gut so that he can enrich a few of his rich friends at Mr. Nielsin's expense. Now, when the Police officers jumped on Mr. Nielsen and forcibly silenced and arrested him they violeted his constitutionally protected right.
Now, I realize that to cognitively challenged kool-aid drinkers, like you, this is no big deal but for the majority of us true Americans who are not cognitively challanged and who are used to thinking by your selves, we are appalled at the gross violation of one of the most singularly important right a person can hold in this nation.
Obviously, that's no big deal to you!