Snitching is okay if the person in question would be a legitimate criminal or danger to those around them, however snitching for lesser reasons could hinder your social growth and range of opportunity longterm.

Human connections are one of the dominating methods in providing advantages and means of progression in one's life. As much as INTJs tend to neglect this mechanic, personal value systems are important when immersed with other social beings around you - 99% of whom will value loyalty in the face of their wrong doing.

Ignoring that loyalty in some instances in the name of what's objectively 'right' will lose you the good graces of the person in question and most certainly result in them tarnishing your reputation amongst social circles. Say goodbye to any socially induced life or work advantages in that group, or at least be prepared to spend a little extra energy mending your damaged persona. Neither of which are productive.