...which they may do under the "sole manipulator" clause.

Even for people who think they understand the FAA's separation between logging flight time and the capacity in which one acts as a crewmember or passenger, it's questions like this that show that the concept remains a difficult one. My bad example of properly logging an illegal activity is really just an illustration of that.

To really understand it, one has to finally grasp that the flight time boxes in 61.51 are independent of any operational regulations other than ones that 61.51 tells you to look at.

For example, 61.51(e)(1)(i) says:
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(e) Logging pilot-in-command flight time. (1) A sport, recreational, private, commercial, or airline transport pilot may log pilot in command flight time for flights-

(i) When the pilot is the sole manipulator of the controls of an aircraft for which the pilot is rated...
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That's a clear box: At least for recreational pilots and above, appropriate aircraft rating + sole manipulator = permission to log PIC time.

There are no other conditions. It doesn't say, for example

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When the pilot is the sole manipulator of the controls of an aircraft for which the pilot is rated... unless he's the SIC in a Part 135 operation
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or, to be completely ridiculous, even

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When the pilot is the sole manipulator of the controls of an aircraft for which the pilot is rated, unless it's a stolen airplane
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It really is that simple and there's more that 20 years of consistent FAA Chief Counsel opinion that says so. But the FAA's decision to use the term PIC to mean two completely different things depending on whether the context is operating or logging will probably always give people trouble.