I'm rarely on, but I just took a quick look at admin, so;
1:Fizz/Someone online more can counter-call me on this but with questions like https://pokemondb.net/pokebase/32049/what-is-a-good-moveset-for-pikachu,
I would allow simply due to age.
A lot of these old posts were valid at the time of posting - as such there is no point trawling through and hiding old posts under new rules; this just sets a bothersome precedent and generally wastes time. As far as I'm concerned, old posts, unless they WERE wrong at time of posting are left alone.
2: I can't speak for other mods/editors, but when I've made this point before about explaining every flag, unflag, hide etc. It provides unnecessary work, and as a general a user takes the initiative to ask (in which said authority will respond), rather than auth taking the initiative to explain every admin decision they make.
I appreciate the difficulty you're presently having though, since you have no idea who did it, and you are putting effort into your flags. However, like I've mentioned previously, flags on just plain outdated posts are rather... meaningless.
Over to oblitigary fizz answer :)
Edit: Pressed hide instead of clear flags, hence why it says reshown.
For the record, I haven't done jackall in admin for a while so :)