YouTube usually won't delete your inactive channel unless it later determines that your channel contains content that it has banned.
Another possible reason for them to take corrective actions on your channel at a later date is if you engage in marketing activity that YouTube doesn't approve of.
But outside of the two cases above, I don't see issues with inactive YouTube channels.
In fact, I do a lot of personal searches on YouTube for stuff that personally interests me. And I pull up old channels all the time.
I'm talking about 10 years ago or more, and they're still around.