-If the guy falls in Mamono-controlled territory, there is a VERY high chance that any unmarried Mamono he meets will find him super-interesting, rape him and make him her husband, and he will never leave. Some Mamono wives may accept to follow him to space, if he manages to repair his spaceship.
-If a Lilim, a Baphomet, a Demon or any other intelligent Mamono with connections to the Demon Army learns about him, she will probably try to find a way to reach Earth, using her powers on him to make him loyal to the Demon Army (she may make him her husband too, if he hasn't still been claimed). Once she has enough information, she would request a meeting with the DL, and convice her to build a portal to Earth using the DL godlike power.
Once they have secured a planet full of potential husbands, the DL unleashes the Demon Army and turn the whole MGE planet into a Demonic Realm. The DL tries to cast her great spell and rewrite the rules making the Mamono able to give birth to boys.
If that fails, it doesn't matter! They have another planet with more than 3,700,000,000 males at hand! (probably MANY more, since No Man's Sky happens in the future) and access to other planets colonized by humans.
-If you fall on human-controlled territory, you may face inquisition because of your heresies. If you manage to convince the high-ups that you really come from another world, they may try to send you back home with a request for military and technological aid.