The ELN (like the FARC and M-19 of which Petro was once a member) fought for social justice in a country run by fascists. But they've long since shed any pretense that they motivated by ideology. However anyone who supports peace should celebrate this deal, and I do believe that Biden will come out in favor and will make a statement to that effect. He did after all invite Petro to the White House for talks in April.

Of note: the "Total Peace" plan being promoted by Petro includes not only left wing guerilla groups but also the right wing AUC paramilitaries (who were even more brutal than the guerillas), as well as the major criminal gangs in the country.