If you are applying for disability with the Social Security Administration they couldn't care less what you have on social media - it has nothing to do with anything they do. When a person files for disability they get medical records, evaluate them and make a medical decision. That is probably true of any government agency, e.g. VA, Railroad, etc, which processes claims for disability.
Frankly they don't have the time to do their workload timely as it is - they sure aren't going to waste it on your social media. You are just a case to them to be processed as quickly as possible so that they can move onto the next one.
But yes, they can look at your social media accounts just like anyone else if it is available to the public. But you just aren't that interesting to them.
I was a SS claims rep for 32 yrs.