Sounds perfectly reasonable to me. Fighting to increase voter turnout is infinitely preferable and authentic to the stated principles of the country than fighting to suppress voter turnout.
When talking about politics its hard to tell whether or not people "believe X because Y" or "believe X because it helps the party". Maybe they don't actually care about X but have meta-awareness and claim to believe X because it helps the party.
This is what makes political discussions annoying and frankly inappropriate. There is no possible way to argue in good faith and people have vested interest in arguing outside of good faith. I'd wager that some people believe they are arguing in good faith but do not realize that they are dramatically influenced by the orthodoxy of their political party.
If you care about democracy in the slightest then you support an increased voter turnout regardless of how it affects your party.