To be honest, I don't see the difference between the two camps going on in this conversation. Let's break this down a bit: either Dalinar is acting as a de-facto vessel, or something, or he is temporarily accessing the power. Either way:
Using that much investiture shouldn't have much restriction on what he can do with it - recall how when Vin ascended, she literally destroyed ruin, which wasn't possible for preservation. So new vessels can act against their shard's intent.
Let's assume that Dalinar, for the purposes of this discussion, will live to a normal age (so like another 20 years or so, maybe? Max, 40-50 more).
There's absolutely no way that his remaining life span, combined with how slowly the intent twists the thoughts of a vessel, to start being influenced by Honor/Unity in any big way. Of course, it's possible he could truly ascend, which would change my assumptions and this conversation, but still not for the immediate future.