They essentially asked whether it would enable users to have privacy and would make it harder for the government to monitor every personal and financial moves of people in the US and around the world.
Well this is one issue that will attract more trouble for Facebook. The Government constantly yearn to control the affairs of the people.. They already have access and keep track of internet presence. If facebook succumbs to the plot of the senators to avail transactional details to the U.S government, the Facebook coin will be a sharp derailment from satoshi vision for the use of blockchain technology.. I hope Mark Zuckerberg stands up to them and give private information regarding transactions private..