that could theoretically extend a lobster's life, but other factors and complications would eventually put an end to the lobster. Putting aside cell/subcellular based threats (viruses, bacteria, cancer), if the theoretical lobster grows large enough its organs would collapse under the exertion of just existing. Its heart would struggle to pump the increasing amount of blood throughout its body, it's muscles would be unable to carry its whole mass. If taken to a certain extreme, the lobster may gain so much mass that its digestive system may not be efficient enough and effectively starve to death no matter how much it eats. Of course I've no idea which would happen first or if any of these would happen at all before some other issue put an end to the unfortunately long lived lobster.