The matter is not as simple as "Either Earth is 4BYO or God is deceitful." For one thing, the very concept of "the appearance of age" can be tricky to employ. Presuming God created Adam and Eve as adults and not infants, is it fair to say "God created them with the appearance of age"? I don't think so. God created them; it's would-be observers who think in terms of "an appearance of age." Is God obliged to imprint a time stamp on the foreheads of the inaugural couple to keep His reputation for truthfulness?
Consider this fictional conversation post-Adamic nap:
God: Well, Adam, here's woman! What do you think?
Adam: She looks as old as me. Where's she been?
God: She's not been anywhere; I just made her.
Adam: But she has the appearance of age!
God: Okay, but I'm telling you that I just made her.
Adam: You expect me to believe that?
God: Would it help if I put it in writing?
When scientists tell me in their books that even though it seems to me that I'm sitting still I am actually spinning around at speeds approaching 1,000 mph, revolving around the sun at roughly 66,000 mph, together flying through the Milky Way at some 432,000 mph, I believe them. Why then, if it were so, could a scientist not be expected to believe that even though it appears to him that the earth is billions of years old it is actually only thousands of years old if God told him so in His book? Is faith to only go one direction? If laymen can trust scientists, can scientists not trust God?
It's not as if God is asking us to ignore appearances. We are flesh, and have to live within them. He's just asking us to trust that there are greater prevailing realities of which we should also be aware.
(I am not here making the argument that YEC is right and OEC is wrong. Rather, I am explaining how "Either Earth is 4BYO or God is deceitful" obscures important nuances and is thus too simplistic a formulation. This is why I say it feels like a false dilemma to me. Therefore, if OEC is right, it is right for reasons other than this argument.)