With the older friction style sway bars, yes, disconnect it. Can't explain the difference in physics for backing vs forward. What I can say is I was with my father in law once and he forgot to, made a backing turn (nothing extreme) and we heard a loud bang. Turns out it was the little ball that WAS on tongue to hold sway bar had blown off. Always heard about it but this is he first and only time I have experianced this.
2013 F-350 SRW 6.7 Powerstroke
2015 Jayco HT 29.5BHDS