Drugs are not tested at expiry dates to know when they age out, they simply make up a number.
Many have used hCG across 80 days with no problems, using BA/bacteriostatic water.
Use by males not originally anticipated. When used for female IVF work with 5000iu in one injection, vials were not expected to hang around. Note that many vials are 5000iu and would be gone in one shot [and then sterile water is an option for that]. Original formats may have been these smaller iu amounts. It is costly to change such info and re-file with FDA or other authorities in different countries. FDA might then ask for lab data demonstrating potency at that longer duration.
In any case, BA water prevents bacterial contamination, so there is no risks from bacteria.