Your father probably yes.

On the other hand: my son was two years and a couple of months old when he got hands on my N9 for the first time. The phone was lying in a couch, screen locked. It took about one minute to get past the LPM screen (after all, there is just one button that makes something when the N9 is locked). In less than two minutes he got past the lock screen. First time swiping it away accidentally, next time he already swiped it away on purpose.

I did not guide him in any way, just looked that he didn't start to throw the phone around or remove any programs. And it took less than 10 minutes for him to learn the basics of the Harmattan Swipe interphase: opening programs and moving between them.

Don't know if Sailfish would be more confusing to use. I probably have to test it with my son when I finally get one.