I believe the reason they are not going after a listing on other exchanges now is because they want txbit.io to shine brightly because it should be listed very shortly on CMC.
There are two main things for Solaris project:
Coinmarketcap.com seems not update exact daily volume in total for Solaris.
txbit.io should be listed on Coinmarketcap.com too.
I don't think people will feel readily to invest in project that have nearly 0.03
BTC in total volume each day. I knew the figure on coinmarketcap.com is incorrect, but if a guess just visit that site to have an overview on Solaris, they will quickly go away after looking at volume.
https://coinmarketcap.com/currencies/solaris/#markets