Social Security v pensions

If a long-term marriage (more than 25 years) ended in divorce AND the wife is ON Social Security, but the husband is not, does her Social Security help protect him from her being able to stake a claim on his eventual pension benefits (after all it's guaranteed monthly income)? Would any claim on his pension benefits be unenforceable/irrelevant so long as he is working and NOT collecting from his retirement? What if she were to die before he took retirement--no one can have a claim on his pension because of her claim, right? (Yes there is an age difference in the marriage.)