This is true but what makes you think that such matters?
The real point here is that the right leaning court overturned something that had been established for 50 years and was a considered by the left not only settled constitutional protections but also fundamental.
What makes you think the left is going to care one iota how well established the second is? If they ever manage to get 5 seats or they simply pack the court directly, they will absolutely overturn gun rights. The fact that the Row decision's reasoning will not apply is not really relevant as it is not the reasoning that brings the second into question here but rather the mere fact a precedent like this was overturned in the first place. That they overturned something that the left felt was firm win for them already is enough IMHO. The reasoning will come after.
It is not as though the left judges on the court have not already voiced their opinion on how the second is not a right whatsoever. They do that with every single gun challenge that comes before the court. The real problem here is that overturning Row gives the future court the cover to revisit almost anything. This is the problem with revisiting things like this, the idea of legal continuity is essentially gone and fights over what is and is not a constitutional right can now persist forever."