Of course, simply because it is possible that people will become lax in accepting Christ if they adopt universalism, it does not mean this is what will happen. Nor does it mean that all Universalists think they can go out and sin willfully. On the contrary, most Universalists are very moral. But, there is the inherent danger in universalism that reduces the need for repentance and salvation. This is a great risk.
Eternity is a long time to be wrong and hell is a terrible place to be forever.
Satan wants the destruction of people. Satan wants people to die in their sins and go to hell. He is utter hatred and complete evil. But, he is also extremely cunning with an intelligence that is vast. Universalism may very well become a tool of the evil one in the last days.