1) name of siding *might* be related to Day & his paper, or to the athlete directly, however Muldoon is hardly an uncommon name. If I were looking for a source, I'd check lists of investors, shippers & employees of the early RGS, those being very common sources for names for sidings. Of course there is(was) that line in NW Iowa (became an M&StL secondary) where the sidings were named things like Mallard, Curlew, Plover, etc. because the guy in charge was an avid duck hunter!
btw, the RGS did cross reservation land (Southern Ute) between Hesperus & Durango, in the vicinity of Ft Lewis Station (MP 148.8) but Muldoon was between Rico & Delores at MP 85.86, nowhere near the Res.
hank
ps Mallard Iowa had a cafe/bar called The Duck Inn...