I think these comments may be a bit on the semantic quibbling side, so apologies in advance.
The question is whether a creationist can give a “coherent explanation” for vestigial structures. The answer is “clearly yes.” This is because coherence isn’t about whether you like the answer or whether the answer relies on belief in the kind of god you believe in. It’s not about Occam’s razor or “theology” or elegance. ‘Coherent’ means literally ‘hanging together’ and the definition in our current context refers to basic logical soundness.
So, if I ask someone how bees fly, and they say “God makes them fly,” their answer may be vacuous or even false (it’s both in this case) but it is also coherent once I make reasonable inferences about the person’s assumptions (in this case, that a god exists and that it is able to make things fly).
I think this is relevant to the discussion of vestigial organs, and you can see why by looking at the kinds of arguments that are made in response to creationist “reasoning.” All of the responses attempt to establish the effectiveness of the evolutionary explanation, but none actually attempts to show that a creationist “explanation” is problematic logically or rationally. The only objection the evolution-defender can raise is that the creationist “explanation” has unwanted implications for the character of the god.
The creationist (a YEC in this case), by virtue of their belief in the poofing of the world into existence by an omnipotent deity, has explanatory carte blanche when it comes to any natural phenomenon. They may sense that it is strategically unwise to play that card too often, but when they do, they are unlikely to be making an argument that is by itself incoherent.
In other words, once you postulate an omnipotent deity, you can only discuss what she/he/it is like–whether she/he it is prone to doing X/Y/Z. You cannot rule anything out without editing the meaning of ‘omnipotent.’ To label the omnipotence card as not ‘coherent’ is, IMO, to use a rhetorical trick that has little or no substance.