[marcinzm]

Facebook would file a counter-claim, project would be reinstated by GitHub (in 10-14 days as required by law) and OP would have to sue Facebook to escalate. DMCA is of little use to smaller entities without money for litigation.

[joshuaissac]

The counter-claim has to be made under penalty of perjury, so Facebook and its lawyers may not do it if they are actually violating the licence.

[marcinzm]

That only applies if they get sued by OP, otherwise there is no risk to them.