This Side Job will start shortly after completing Riders on the Storm, so soon that you probably don’t even need to skip time to get it to appear - simply driving to a nearby fast travel terminal might do it. Just keep an eye out for an “Undiscovered” quest marker near the Mobile Camp fast travel terminal, as you only have a short window of time to complete this quest. Ideally you’ll do it immediately after Riders on the Storm, but before With a Little Help from My Friends.
When you see the quest marker (you should also get a text from Mitch), track it and head over to the marked location to find Mitch, who will ask you to help him tie up some loose ends for Scorpion’s funeral. Agree, follow him to his car, chat some more, get in the car, and drive off after Mitch.
Follow Mitch to the collapsed bridge and talk to him to find out just exactly what he’s up to. Respond how you will, then go get a gas can and put it in the passenger seat of the car he drove here. After some more chatter, do as Mitch asks and light the rag in the fuel tank and watch Scorpion’s send-off.
Mitch will offer you a drink. Be sure to accept by respond with “Sure thing.”, and after a while V will ask Mitch why he invited an outsider here. After he explains, the mystery of Scorpion’s name will come up, and Mitch will give you one of Scorpion’s possessions, an Action Figure which you can use to decorate your apartment.
Not only does this action figure explain Scorpion’s inspiration (at least, assuming you’re vaguely familiar with one of the major fighting game franchises over the past quarter-century), but it’ll finish up this quest.