The situation surrounding his exclusive rights is a bit blurry.
Drafted in 2017, at the age of 20, the rights are only 2 years. But then he signed in the KHL at the start of this season which would mean his rights don't expire (no transfer agreement between the NHL and KHL). 2 months later, his contract was terminated due to financial problems with Slovan, and he moved to Örebro (SHL). That could mean his rights carry over another year, or that his rights go back to expiring in June 2019.
I think the Rangers would at least like to give him a shot. They currently have 7 slots open, with O'Gara, Tokarski, Gilmour and Brickley UFA this summer, and Bergman moving to Sweden.
That gives them 10 open slots, since Keane already takes up on. Shestyorkin, Rykov and Kravtsov are another 3, leaving them with 7. Contract slots aren't the issue