Roland had dealings with all members of the "Seven Deadly Sins." His remark about those seven was "a band of villains who know nothing of restraint."
Just like the names of the sins they were given, the Seven Deadly Sins are evils that lead the heart to fall as various desires swell. Essentially incompatible with virtues like "restraint" and "patience," more so because Li Lin simply viewed them as pawns for handling various under-the-table jobs, never teaching or guiding those guys, so there's no reason to hope these born wild ones could turn towards good.
If you don't want to get killed or get screwed over and want to live a few more years, it's best to stay as far away from the "Seven Deadly Sins" as possible. Even if you're suicidal, there are other ways to end your life, no need to use such a brutal method.
