Odell Beckham had every right to go scorched earth on his former team and his ex-boss in a Twitter rant ... so says DeAngelo Hall -- who tells TMZ Sports the Giants deserved it!!
The ex-Redskins star -- who's doing NFL Draft coverage this week for FS1 -- says, "I'm cool with [Odell] venting because I felt like the Giants GM was out of line!"
Of course, if you haven't been keeping up ... Odell and the Giants have been in a tiff since Big Blue traded the star WR to the Cleveland Browns in March.