Last time I checked (maybe 2019 or 2020), FIPS only permitted RSA for public-key cryptography. 1024-bit keys were no longer permitted, IIRC. If the company was involved in business with the USG (and many large companies are), they may have needed to comply with FIPS in some way (pure speculation). (Or the recommendation may have been on that basis, even if FIPS/USG was not involved in the ssh use.)