I'm not even sure what words they're censoring, that might not even be it potentially. If it's 술 then you'd get like 500 other words stuck in context with it like I dunno, 요술. Filtering for certain words is probably a lot easier in Korean than in English and concatenating that all together is probably about as easy to guess as 13375p34k in English.
Haha I like that. Most likely will be ㅁㅈ though unless that's already on the list. Anecdotally I've seen whole messages written using the first piece of the Hangeul square. Seems like that would be a nightmare to keep track of for these programs and relatively easy for kids to perfect.
