It's not terribly uncommon to see bad teams have goalie with high SV%. Teams without defensive talent usually rely on systems to take away high danger areas. Give the opponent lots of shots to the outside, protect the inner slot, this is stuff you learn in bantam. SJ may give up 35 shots a night, but when you have 5 skaters turtling there are not always as many high quality chances as you think.
Higher shot volume means that each goal has a small impact on your SV%. 2 goals on 20 shots is .900%. 2 goals on 40 shots is .950%. The later looks much more impressive, but if they're weak muffin shots from the outside then you're padding your numbers with empty calories. Not all shots are created equal, which is why SV% is such a flawed metric.
I know the Sabres had some guys like Michael Neuvirth and Carter Hutton put up some decent numbers behind terrible defenses. The mid-2010s Coyotes had some similarly overperforming goaltenders like Mike Smith and Darcy Keumper. High shot volume pads your SV% while not necessarily increasing the difficulty of your workload, which lets some sub-par goalies on bad teams put up superficially decent looking numbers.
It sounds counter-intuitive, but sometimes facing more shots against is actually easier for the goalie. More shots doesn't necessarily mean more chances to score, it can also mean more chances to save. Goals and shots are both stochastic processes, but one has a much larger scope of variance than the other.
This also works in the opposite direction, if a goalie faces fewer shots then his save percentage is more volatile because the goals he does allow impact his SV% disproportionately. I have always suspected this contributed to Marty's otherwise pedestrian career SV% - the defense in front of him and home bias at CAA robbed him of a lot of easy save. If Marty gets 2 more saves a game his SV% goes from .912 to .919, and 3 extra saves per game brings him up to .922.
I know Dr. No did a bit of research on the analytics board before the server migrated, I don't know if that data is lost or not. But I remember most goalies see their SV% increase with high shot volume. I think every goalie he looked at had a higher SV% when facing >35 shots a game than facing <25 shots a game because more saves = higher SV%.