ahhh, no problem :) when you say he does pseudo-architecture work, you mean like he keeps a portfolio or something? im assuming he's not done the photography shtick before or he wouldn't be asking you for advice haha.
is there a specific reason he wants a mirrorless camera? is it for portability? if you guys are well off and can afford a dslr, i would actually just recommend getting one of those. it's not like a mirrorless camera is going to fit in your pocket anyway since you still have the lens(es?). and it would be super awkward to put it in your coat pocket since it's no where near as small as a point and shoot.
i think the main draw of mirrorless cameras is that they're light and pretty small. they're pretty popular for travel since you typically are walking around and exploring new places and a dslr actually starts to get pretty heavy after a while, especially if you have 2-3 lenses with you. but if your dad wants this specifically for architectural purposes, then i don't see why weight/portability would be a plus since he'd be going on location specifically to get a certain shot, etc.
anyways, "extreme detail" has more to do with resolution and lens than it actually does with the focal length. resolution for cameras is measured in megapixels (MP) and if you search any of them on amazon all of the models will have the number of megapixels right there in the product title. just to give you an idea, a 12 MP camera gives photos that are about 4200 pixels long on the longest edge. my current camera is 24 MP and about 6000 pixels long on the longest edge, which is A LOT and probably far more than most people need.
also, you said your dad does architecture shots so i think i can at least point you in the right direction here. he'll probably want a wide angle lens. i think i probably have to explain a bit more on thsi point:
all cameras have a sensor. it basically converts the light to a digital signal. in the film days, sensors were about 36x24mm in size. digital cameras that have a sensor in this size are typically called "full frame" cameras (quite expensive too). many of the consumer models of dslr's have sensors that are much smaller, around 24x16mm (usually called "crop sensor"). this means that lenses capture a much smaller portion of the image than a "full frame" sensor would.
going even further, mirrorless cameras usually have an even smaller sensor. for example, the nikon v1 i linked you to has a sensor that is just 13x8mm. sensor size is linked to image magnification.
for example, a 35mm lens on a "full frame" camera is considered standard view. if you pointed the camera at the person next to you, you'd be able to get their entire face into the shot. if you were to put a 35mm lens on the nikon v1, it have a magnification factor of x2.7, ie if you pointed it at the person next to you, you'd get like...their eye. because effectively the focal length becomes 35x2.7 = ~95mm.
the sony nex-7 i linked you to before is interesting because they managed to fit a 24x16mm sensor into the mirrorless format, so it's essentially very similar to a prosumer DSLR model fit into a much smaller body.
i went into so much detail here because the lens(es) your dad will probably want are completely dependent on the camera he gets. for instance, olympus mirrorless cameras are micro 4/3rds format, which basically means any lens you slap on has a x2 magnification, roughly speaking. but the sony nex-7 has a magnification of only x1.5. so i'm not sure what focal range he needs until he has a specific camera in mind.
i'm slanted towards the nex-7 though...i've always wanted to try it and it gets fantastic reviews. but again, if your dad wants "superb" image quality, i don't think a mirrorless camera is a substitute for what a proper DSLR can do. just my $0.02. can't really give much more than that without knowing more about what he wants. and i also reaized how badly i rambled in this post... -_-