To understand, we must remember that the Constitution specifies what the Federal Government may or may not do not what individuals may or may not do. Limitations on citizens are called “Laws.”
The Federal Government may not consider the individual guilty or punish the individual when the individual claims the Fifth Amendment. Citizens may. There is nothing to prohibit citizens from believing an individual guilty of a criminal act and acting accordingly toward that individual when that individual claims the Fifth Amendment. After all they are admitting that if they testify they will be a witness against himself in a criminal case, just as the Constitution says.
Today it seems the Fifth Amendment is used whenever an individual does not want to testify; when testifying might cause embarrassment; when testifying might make public some information the individual does not want made public. What follows is Amendment V (1791) in its entirety.
No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a grand jury, except in cases arising in the land or naval forces, or in the militia, when in actual service in time of war or public danger; nor shall any person be subject for the same offense to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due process of law; nor shall private property be take for public use, without just compensation.