mbyron,
Regarding the "status of the J/R "relaxed/unrelaxed" interp in pro ball", those terms do not appear in OBR. But as UmpJM points out in
the no-tag thread, MLBUM 5.3 clearly employs the idea. (It's worth reading that thread: JM quotes 5.3 from the MLBUM, and a poster named mbyron make some good points.) Additionally, we know that an appeal "must be made before the next pitch, or any play or attempted play", yet the MLBUM says that if an appeal is interrupted to make a play or attempted play which occurs as part of continuous action, then the defense may subsequently renew the appeal (5.4 1, 2, and 3). On the other hand, the appeal is no longer possible after a play following a "definite break in the action." Official OBR interps certainly use the general idea of "relaxed/unrelaxed", even though that terminology isn't invoked.
However, I haven't seen any discussion of 7.10(b) vs. 7.10(d) in the MLBUM, so it's not obvious that the J/R interp would stand.
About "literal reading" of 7.10(b): By literal, I intend just that-- "touch" means touch, not pass close to. I think trying to use "missing a turn" while driving as an apt analogy for missing a base is abusing the many meanings of the word "missed". Perhaps a better analogy would be 9 ball billiards, in which the cue ball must strike the lowest numbered ball on the table before it can strike any other. The cue ball isn't deemed to have struck the balls out of order until it actually strikes a wrong ball. Or consider a sick person who needs to visit the lab, a doctor, and a pharmacy--in that order. Even if he drives most of the way to the doctor's office before returning to visit the lab, he still can do things in the proper order, and hasn't yet done them in the wrong order.
Of course, we don't employ a literal reading of 7.10(b); it is just one of the "234" errors in OBR. So using the letter of 7.10(b) as a reason for not extending 7.10(d) has a dubious basis: the rule is already wrong, in the sense that we don't interpret it literally.
Childress comments: "The Committee intended the material quoted above ['while advancing or returning to a base, he fails to touch each base in order before he, or a missed base, is tagged'] to cover a runner who left too soon on a caught fly ball. The ambiguity of the language forced the interpreters to 'revise' the ruling....."
Finally, I got carried away in suggesting that there is a time frame for announcing an appeal (aside from the trivial before the next pitch, etc.). You're right; the requirement is simply that the appeal be unmistakable.