Yes, as long as one’s only goal is producing a well-behaved (neutral gray axis) ICC profile, it doesn’t matter what source or destination white point or even what xy values for the primaries you choose. As long as the resulting XYZ values are properly “nudged” (which ArgyllCMS does do, and LCMS does not do), the resulting profile is “well-behaved”. Well, most profiles with D50 source white points don’t need nudging, and not even all the color spaces wtih non-D50 white points need nudging.
As a complete aside, I’m guessing there are practical limits to what can be used as source color space RGB xy values. For example, what happens if you choose three primaries that are all on the spectral red and yellow side of any normal white point, and not including a primary on the other side of any actually “white” white point? For such a color space, it would be odd to speak of a neutral gray axis. In another thread this type of profile was suggested, but I never did take the time to make such a special-purpose profile (and I’m not sure my profile-making code would even be able to make such a profile). If you are curious, here’s the thread:
I am very happy - thrilled actually 
- that so many people on this forum and in this thread are taking the time to read the ICC specs and also even read color space specs.
Like @saucecontrol, I’m not willing to spend money to get copies of the various official latest color space specs. But if anyone uses exiftool to examine my ICC profiles, I do give the link to the version of the spec that I did use, right inside one of the ICC profile tags.
Thanks! And also thanks much! for clarifying regarding the D65 white point.