The fallacy is comparison to perfection. Commonly known as the Nirvana fallacy.
It is a common rhetorical maneuver. The person performing the move compares all opponents to perfection, finds them imperfect, and concludes only their own proposal is acceptable. They are usually careful to avoid comparing their own position to anything, relying on their opponents to be honest enough not to do the same move, even when facing it.
A correct understanding of such situations is that perfection is almost never obtainable. (I don't have an example of perfection in real life, but I cannot support a claim that it is never obtainable.) Thus we must (usually) make comparisons on the basis of different options being relatively preferable. We must examine the choices on the basis of imperfect data and imperfect understanding, and choose the option that seems the best overall.
For example, the gun laws. The correct objection is to ask how the new proposed laws will make a difference that the existing laws don't. And what the data is that supports such claims, what the costs are of the new laws, etc. and etc.
In each case, the mover will change the discussion to a comparison with perfection. This can be proffered up as either a reason not to change the existing conditions or a reason to reject the current conditions. Existing laws are not perfect so must be changed, or, proposed laws are not perfect so cannot be accepted.