Yes, youngmafbog, that's what lawyers jokingly call 'jury equity', from the branch of the law called Equity, which is the application of established legal principles of fair play and justice to override strict interpretation of statute or precedent.If you can conjure up any 'defence' which gets past the judge ruling that it isn't one, the jury may feel that the accused really ought not to be convicted and punished and, though they think he is technically guilty, acquit.
Problem is to think of such a defence. They might try arguing that the man genuinely believed that he was in loco parentis and entitled to act as a parent. Not sure that such a mistaken belief would amount to a defence in child abduction; it's not like mistakenly taking an umbrella in a stand because it's identical to yours, which can't be theft because you're not acting dishonestly; but it's worth a run, perhaps, however much the claim runs against any obvious facts.
Chances are, however, that his counsel will advise him to plead guilty to that count. Counsel won't invent a defence; tell the client to give a different account to that which he's giving just to make a new defence fit;and if this man comes up with such a fanciful version, his counsel will test it with him, cross- examine him on it, and ask him to apply some common sense, which the man will do.