I'm not sure he was available, available. If Tobias/Tkachenko officially teamed up right after the 2014 season, then chances are Tobias knew Stagniunas was planning to retire and was already in talks, or, Tkachenko wasn't interested in continuing, but when presented with the opportunity to skate with Tobias again, decided the offer was good enough. By this time, he was older and married, and, perhaps, his wife thought it would be a good opportunity.
Back in the day, when he described his American partner's father's private helicopter that took them to practice, he said that he was happy to have a Russian partner and represent Russia at the highest levels. Teaming with reigning Olympic Bronze Medallist Ilinykh would have given him an excellent shot at being the highest-ranked Russian team shortly out of the gate with a chance for a high international placement, especially with D/W and V/M out of the way for at least one season, and the Russian Fed's lukewarm support for B/S. So if there were serious talks about the potential pairing/interest with Ilinykh, either 1. His priorities changed since the first time they (T/T) skated together, 2. He decided that skating with Ilinykh wasn't worth it, or 3. There was a sekret tryout that didn't work out and, improbably, no one leaked it.