Can a job fire you due to Covid-19?

Where does your friend work at and what exactly is his proof you vaguely mention? Does your friend have: A) Hard copy medical leave instructions/documentation from his workplace HR Department? B) Hard copy medical documentation detailing his doctor's office visit and any physician's documentative notations about any treatments, testing, etc...??

Generally, most work offices instruct employees who take off work for medical reasons to provide such medical documentation--which is kept under strict confidentiality discretion handling within the HR Department, as per any labor laws governing that particular U.S. State as mandated under Federal law(s) as well.

So your friend DOES have rights to file for unemployment AND he also should look into filing a complaint with the EEOC office under the State of Georgia. Seeking a consultation with a reputable labor law attorney is recommended as well.

Also something to consider: It's possible there are a few "workplace political dynamics" hiding behind HR Department stated workplace medical leave policies as their TRUE reason(s) for them career terminating your friend. 

If that IS the REAL reason your friend was "career terminated", then it's evident they simply don't want him working for them anymore--so why then would your friend want to continue working for someone who doesn't like him in the first place?

Even IF your friend is legally protected in being career reinstated---his angry boss(es) will simply lay in wait for finding another opportunity to end his employment.

So even IF Georgia employment law AND Federal employment laws favor your friend's career reinstatement......it just might be better he seek better employment opportunity somewhere else. 

If you can prove that he was fired because of COVID-19, and he has not taken 12 full weeks of medical leave, he ought to be protected under the family and medical leave act (FMLA).  I would imagine if you sued, you would win.  However, Georgia does not have its own medical leave legislation.  It would be under federal jurisdiction, which can be problematic if you don't live anywhere near a federal courthouse.

As far as I know, most states are "at will" employment, so they can fire you for pretty much no reason at all.

In a true free-enterprise system employers can fire anybody they want for any reason or no reason at-all 

just as he can quit the job at will so a employer can fire you

the more you explain the less it made sense

some say sue.... OK sure
but no lawyer will take the case without you paying huge up front - retainer 

there is no money in the case and so lawyer will not help you 

reality is life is not fair deal with it move on do not dwell on this 

You should be asking a lawyer

Georgia is a republican state. So i'm going to assume its a right to work state. Which means fire at will. The virus. You might have something here an attorney  can work with. Not sure.

It seems as though something is missing here.  While ypur fiancé came forward and told his boss he had been in contact with someone who had the virus, that could be true for many of us, so whether or not we tell our boss, it shouldn't cost us our job.  Your fiancé should have been tested when he was asked to take his break from work, and definitely before he returned. Have your fiancé contact your state's Dept.of Labor for a hearing on this.  When they investigate the "proof" presented by both sides, they can determine if the termination was, or was not, legal.

 Yes, if your a threat to others working environment, SECURITY_GUARDS/COVID--19K1O0000_USA&FEMA, can have you fired...?

Did he get a doctors note?

Yes they can fire you for any reason, but you will be eligible for unemployment compensation.  If you were fired by cause then you wouldn't be eligible.