The universe appears "old", but it is still less than 10,000 years old

[Esquilax]

If I believed the Bible was the word of God as Christians do, why would I not be?

That's an answer with a lot of wriggle room.

Additionally, do you respect Old-Earth Christians more or less than Young-Earth Christians and why?

Why would an atheist not respect old earthers more than young earthers? The former has at least made an attempt to do something that, generally speaking, agnostic atheism is in favor of; modulating their beliefs to fit the available evidence. The fact that they've done so imperfectly doesn't detract from their effort.

Granted, one might see it as inconsistent, but that really depends on where you're coming from; if you have a position you've taken to be the ideal one, and any deviation from that represents a contradiction or weakness of belief, then yeah, it's inconsistent. If your only wish is to best align your beliefs with the facts, regardless of what they are, then it's just forward progress.