Karma won't kick me for laughing, right?

Background:  my parents up and moved to the East Coast (from SoCal) about a year ago.  They are originally from there and wanted to move back, despite the fact that we live in CO and my bro and sister are in WA state.  None of us so well off as to fly and see my parents every year and they plead that they can't either. 

They are currently visiting my sister.  They are staying at a nearby motel as they timed their visit to coincide with my sister's ILs visiting from Ireland.  I just got the first of what I am sure will be many (per past protocol) email from my sister going off about my parents -- how they are never there, how they are hyper-critical about the kids and my sister (to the point where my 5YO nephew told my sister "I don't like your dad"), my dad has already offended my sister's MIL with his uber right-wing gun-nut stances and tirades. 

All I could write back after laughing was I was glad that my parents visited them (my sister is the clear fav of the kids) and that my sister is NEVER allowed to move near me.