If the bacteria is truly ancient, then the first consequence is probably not just a revision of the molecular clock concept, but perhaps an abandonment of molecular dating as valid altogether.
I don't see that. The worst I could see would be to change an equality to an inequality. That is, a measurement of age based on the amount of mutation might set a lower bound for the age instead a providing a reasonable age estimate.
But you are jumping the gun. As others have indicated, there might merely be a problem of contamination, resulting in bad data. Until you have eliminated that possibility, you cannot conclude anything. And even if that possibility is eliminated, further experimentation would be needed to better understand what is happening. Science theories aren't just invented on a whim, they come out of careful studies that attempt to understand the processes involved.
The evo stance is that environmental conditions would dictate stasis due to a lack of pressures to select for mutations.
As indicated before, I'm not a biologist. My knowledge of bacteria is particularly limited. For sexually reproducing creatures, one must distinguish between phenotype and genotype. My own view is that we should expect to see gradual evolution of the genotype, but punctuated equilibrium (periods of stasis and bursts of change) in the phenotype. During a period of phenotype stasis, the genome could be building up variation with mainly unexpressed genes (or rarely expressed genes), and at a later time and under selection pressures, some combination of the new genes could lead to relatively rapid change in phenotype. The change would involve some reorganization, in that rarely expressed genes would now be more commonly expressed.
So let's consider that we have evidence of bacteria evolving very little for 250 million years, and we cannot justify that is better suited in it's niche.
Only if that can be seen to happen for all organisms. That one particular group did not evolve, would just show an interesting peculiarity about that group.
I think it best to wait till all of the evidence is in.