The culinary science in this episode is sound. Honey and pineapple indeed contain proteolytic enzymes, which tenderize meat remarkably quickly.

I've done pineapple and pork kabobs. Pineapple makes incredibly tender meat, which can otherwise get dried out on the kabob when you're trying to get the vegetables done. The pineapple does have to be fresh. Cooking and canning destroy the enzymes.

It isn't the common way to do things, because as Soma pointed out, buying an entire pineapple for a dish is unfeasible in Japan where they are rarer (and likely also expensive), and honey isn't exactly cheap either.