"However, I have seen many times that some of the people who gather together to discuss these things don't enjoy the long talks about it, they are just doing it to please their friends who are gathered with them. In such a case it would seem that there would be a concern of Issur for those who don't enjoy it."
What he is saying is as follows: The ...
In Shmiras Shabbas K'hilchasa (chapter 42, 58) it states:
"יכול אדם להתחיל בקריאה זו
של שנים מקרא ואחד תרגום מיד אחרי תפילת מנחה בשבת אחרי שקראו בציבור את הפרשה הרשונה של השבוע הבא״
Now it would seem that one can only start doing Shanyim Mikra V'echad Targum after having davened mincha with a congregation, as is seen from the italicized text. However ...
Rabbi Azriel Rosenfeld says that when on a different planet, pro-rate the length of the day or the year. On Mars, a "day" is 24 hours and 39 minutes in earth time and a "year" is 687 days in earth time, so you must modify observance of the calendar accordingly.
As long as putting the baby in the swing would not cause any extra melacha to be done, this would be permitted. The same is true of the Shabbos elevator - those who forbid its use do so only out of concern that the force of the person entering the elevator may cause lights to illuminate and such like.