If we take a "gun ownership"->"suicide" relationship for granted, we cannot assume that this particular gun owner is at risk for suicide. If there is a trend, then we can talk about the trend and populations. However talking about individuals requires more care.
I think the argument only applies depending on your definition of "risk for suicide" and whether you believe there are people who never under any circumstances in their lives feel suicidal even for a second before snapping out of it.
Killing yourself requires two things: the will to do it and a means. If you have a loaded gun, the means is a constant: at any point in time you have it you could use it to kill yourself. Will, on the other hand, is a function dependent on a bunch of things: bad news, time, emotional state, social interactions, etc.
I would define "risk for suicide" in terms of the combination of both will and means. As such, unless the individual's will to commit suicide is absolutely and always zero, adding a reliable means would always increase risk of suicide. I guess it's up for debate whether there's anyone on the planet who has never felt suicidal for even a second in their lives.
If we take a "gun ownership"->"suicide" relationship for granted, we cannot assume that this particular gun owner is at risk for suicide. If there is a trend, then we can talk about the trend and populations. However talking about individuals requires more care.