Short version of the objection: if you meet a vampire and need emergency protection from evil, but your faith is strong enough to compensate for the MacGyver-like improvisation you'll have to do when you want a crucifix but settle for a can of Spaghetti-Os, then almost any implement answers to your need, because it's incidental to the contest of wills that you're having.
Fortunately, nobody in the conversation seems ready to abandon the idea that "well begun is half done." Tools matter. In this instance, they speculate, it's not either faith or crucifix that you should arm yourself with, but both faith and crucifix.
Mr. Wright adds an excerpt from a forthcoming novel (Somewhither) to the proceedings, and the excerpt fits.
Other fantasy novelists have wrestled with the same question, of course. Interestingly, the consensus view of the people chatting at Mr. Wright's blog seems to be that Larry Correia's Monster Hunter International books are weak on this point, whereas Jim Butcher's novels about Chicago wizard Harry Dresden are well-educated. Based on what I've read of those authors, I agree with that consensus.