To know for sure how much aliasing is present on the rivets, you would need two shots with the camera displaced slightly. The form of the alias (as constructive or destructive of a small detail) does depend on the relative position of the detail and the pixel structure. This is much more obvious in a motion imaging device if the camera moves slightly.
The first devices to invoke serious consideration of aliasing were standard definition television cameras, because of the relatively coarse scanning line structure, equivalent to 480 pixels per picture height. This was so coarse that you could never escape a compromise between small detail contrast (vertical frequency response and sharpness) and aliasing. In tube cameras, the aliasing was relieved by making the scanning spot blurry enough so that the scanning lines essentially overlapped their neighbors. In addition to the simple spatial aliasing, there was worse aliasing due to interlaced scanning, also relieved by the blurriness of the scanning spot. When TV cameras went from tubes to CCDs, the CCDs had to be designed to average two adjacent rows of pixels for each interlaced field in order to reduce aliasing to an acceptable level. Then came high definition. With about 1000 rlines (rows of pixels), the aliasing was much less objectioanble, parlty because the lens was now a prefilter for antialiasing. The CCD now could have a variable amount of averaging between adjacent rows to give a choice of more detail contrast (but with some aliasing) or less detail contrast (but cleaner). NOTE that this is still a motion imaging case, so you have to go more towards clean than towards detail contrast, since whenever the camera moves, the variation in the alias components may be objectionably strong.
For digital still cameras, since you do not have the temporal variation in the aliasing making it so obvious, you may get away with a much higher level of aliasing, which gives greater sharpness, albeit with "false" detail. It's a matter of taste. My personal taste for a sensor with the high resolution of a DSLR is to keep the antialising filter and boost the detail contrast with post sharpening.
On the other hand, in designing consumer digital converter boxes to go from high-definition broadcasts to analog TV sets, it has been found that a filter that completely eliminates aliasing looks far too soft - it's back to the same trade-offs as for a standard definition TV camera - some detail and some aliasing.
Also by the way, there is a similar principle in loudspeaker design - a mid-range driver with a small amount of distortion will make a speaker sound like it has better high frequency response than it really does - but the high frequencies are being generated in the speaker and didn't really come from the source. Depending on how much distortion is present, some sources may not sound their best.