This is not true at all. Though the detrimental impact of ageing is more pronounced on Oocytes than on sperms, it would be incorrect to say that age has no effect on mans’ fertility. After the age of 40, it has been observed that sperm counts fall and other semen parameters like motility deteriorate steadily. Therefore the chances of conception also fall with an increase in mans’ age. It has also been noted in many studies that an increase in paternal age leads to many other disorders in children like subfertility and mental disorders.
Please visit this link for more details: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2566050/