The job posting is in bad faith because there is no reason given to prefer men over women. Even if it were an office job where a woman quit because the lifting was too much, it still doesn’t mean that you should prefer men over women. Most women can do the job, I know this because I’m a woman who is below average in size and strength and not only is 25 lbs not a problem, but I’ve had many jobs that required heavy lifting and I’ve never had an issue. There is no office job on this planet where I wouldn’t be able to cut it even if it meant lifting many boxes throughout the day. The only time it would be an issue is if that was what you were doing all day in which case this would not be considered an office job. Preferring to hire men at this level of physical work (even multiple boxes) implies that men are more capable at this level, which they are not.