DJ is DJ. Basically he’s a subpar zoner, subpar vortex, with subpar pokes lol. But srsly. There’s certain maches you can get away with being overly turtley, Ryu isn’t one of them which is probably why you have trouble. Ryu like most other fireball characters beats DJ in fireball wars, meaning eventually you’re going to have to get in on him. So yes you have to go offensive. Also DJ doen’t have great reversals or tools to deal with pressure, that’s why you can’t just turtle everything.
To me DJ’s offense/pressure is just as important as his defense/zoning. And after a certain point, at high levels and when your opponent is familiar with the matchup you have to play more offensive to get that damage off the voretx. They block the right way and then what? they tech now what? You start using frame traps/tick throws/more offensive prssure/baiting/reading them and adjusting etc. thus making your offense better. Certain characters/situations you don’t want to keep the vortex going also. Like if you have the life lead, if the opponent has ultra/super, or good reversals etc. Better to just go with the good combo, get the damage, and back off and play it safe.