I can argue both ways:
ARGUMENT FOR PLAYER A:
In general, I agree with your first impressions (i.e., either Player A should have kept shooting or a re-rack should have resulted). However, that’s not the case here because you stated that, “They did agree that there was no foul committed but that Player A lost his shot. Player B got up to the table and played the shot with the cue still frozen to the 8.”
Therefore Rule 1.23 seems to apply and Player A wins because he was able to manipulate Player B into shooting the next shot. (Rule 1.23: Fouls Not Called -- “Any foul not called before the next stroke is taken is considered to have not occurred.”)
Comment: The only foul that Player A called on himself was Rule 1.17.3 (i.e., “You must always call shots that are defined as not obvious. This rule applies regardless of whether or not your opponent asks about the shot, and regardless of how simple or obvious the shot may appear.”) So, if they agreed that there was no foul (i.e., violation of Rule 1.17.3), then Player A made his bank shot and should have remained shooting. Player B (and his captain) were chump(s) for agreeing to no foul and then shooting.
Rule 1.23 prevails and Player A scores a win and gets to pat himself on the back for successfully manipulating the rules to his benefit.
ARGUMENT FOR PLAYER B:
The 2010 BCAPL player’s handbook states on page 65 under applied rulings for 1.45 unsportsmanlike conduct:
“Particular sensitivity will be applied to issues involving communication between players. Attempts to manipulate the rules concerning communicating and acknowledging called shots, safeties, or other required information will receive special scrutiny. For instance, acknowledging a called shot or safety with a barely perceptible nod and then trying to claim later that you did not acknowledge the call will be considered unsportsmanlike conduct. It is incumbent on both players at all times to ensure that clear communication takes place.”
Assume that the rule book was not thrown on the floor and the opposing team captain was not called a vile name (i.e., sufficent justification alone to rule loss of game for unsportsmanlike conduct):
IMHO, since Player A waited 30 sec. and called the foul on himself only after considering his lack of shape, it seems like Player A tried to “manipulate the rules” by requiring that Player B accept his interpretation of the rules and forcing Player B to shoot the next shot. Because, it seems to me like the only “sporting” thing for Player A to do would be to also allow Player B the option of shooting or not (i.e., being able to decline the “bullcrap” foul if desired).
Furthermore, since they agreed that there was no foul (i.e., there was no violation of Rule 1.17.3 and that Player A therefore legally pocketed a ball), it seems to me like unsportsmanlike conduct for Player A since he clearly knows the rules and still argued (against the rules) that it was Player B’s turn to shoot.
Comment: The only way I would consider Player A’s actions “clever” is if he had declared a safety in advance of shooting.
To the OP and league operator, good luck with your decision.
In the future, if you have a cell phone, suggest you give everyone your cell phone number and ask people to call you if there’s a ruling that needs to be made. That way you can make your rulings real-time and nip most problems in the bud before play proceeds and the aggrieved party looses the game.