Following are the reasons i found with personal experince after interaction with people and their comments and reactions.
1-----They have their won beauty standards degined for women in their mind which do not match with a muacle women.
2---- They feel threat to their musculinity when a women is stronger and has muscles.
3---- They just go with the society sterotypes amd never give a thought about it.
4---- It hurts their male ego and think its embarressing fot them and are scared of society reactions and comments