The IRS doesn't use your online profile to decide if you're a tax evader. It's simply fearmongering from anti-tax advocates.
The IRS doesn't even have the budget to carry out basic audits in which the bulk of the investigational burden is placed on the taxpayer (by means of responding to auto-generated documentation requests). It certainly doesn't have the budget to invest in a high-tech system that could track multiple social media platforms and somehow connect that to financial spending or tax reporting.
