Did the Sun Capture Sedna from Another Star?

A delightful (if hard to understand) paper, that posits that Sedna (and friends) were captured from another star in a close encounter. What's not to like about the possibility of alien planetesimals in our system?

http://arxiv.org/abs/1506.03105

Sedna Perturbed By A Super Earth? 
An undetected super Earth is one explanation for the odd orbits of Sedna and 2012VP_113. A (new) ninth planet makes for great writing material (I have a group that may want to head there). However, I'm skeptical about a new planet. What's a large planet doing in a region of space, where everything seems to be crumbly ice balls? I haven't the science to qualify that question, so let it be stated that this is just bias. 

Having stated my bias, I'm going to continue with it. 

Picture Credit: M E Brown, Caltech

Sedna Perturbed by a Star Q?
Jilkova et al. model an encounter between the Sun and a star "Q," which would have been 1.8 solar masses. By their calculations, both stars would have exchanged several hundred planetesimals. Some would be "Sednitos," with similar orbits to Sedna. Others would be in the inner Oort Cloud. The estimated distances range from 30-1500 AU. 

Perturbed Writing?
Both a new, large planet, and captured, alien, icesteroids, are great writing fodder. Frankly, its hard to choose between them. Consider the super Earth. Even Pluto has its own little system of moons. How many could a super Earth have? How big could they be?

The bigger a super Earth, the better. Radioactive decay from within the rocky matter would heat volatile ices into liquid. We could expect an ice crust over a liquid ocean. The more heat from decay, the larger the ocean could be, and the longer it would take to refreeze.

So, at the very least, a super Earth and its moons could be home to various communities (refugees, hiders, hermits, abominations). Undersea life would be a strong addition. Scientists could study it to test for panspermia, contamination from Earth (or Mars), or Sharov and Gordon's Moore's Law of life. Alternatively, the life could be completely indigenous.

The View from Sedna. 

Picture Credit: Adolf Schaller

Planetesimals from another star though, are at least as useful. They could be life-bearing. Would it be utterly unique, or share ancestry, fellow scions of galaxy-circulating microbes?  They could carry probes or self replicating machines, sleeping quietly like Philae, waiting to get dislodged and transferred to another system. Perhaps they carry cryo-freezers, tombs - or prisons?

If the "Q" hypothesis wins out, then a sampling mission becomes something we should aspire to. Aspiring projects are always good writing fodder.