It is subjective indeed. There are many questions along that line in "the site" forums, you can search those and read the mods responses. I had some rejected games with the same reason in the past, so I searched through this stuff myself. In short: Browser (flash) games, and PC games by platforms like Steam or Itch.io are held to more scrutiny, and won't be accepted if they aren't notable and have anything special to them.
Many of those games can be seen as kind of clones of each other in terms of gameplay, while only the appearance is changed. by looking at the type of your game, the site is full with 3D exploration/first person view/point-and-click games which can be completed in really short times. While it might take a casual player to complete this game in 10-20 minutes in first playthrough, just you saying that this game can be ran in 2 minutes is a proof to how short it is, without any special stuff happening in it (just by first glance on a playthrough of this game on Youtube)
Defining "short" games is also subjective, yes, but some of them are universally short. If it can take a casual player less than 5 minutes to finish the game then it will probably not be accepted. Note that there ISN'T any hardcoded threshold for shortness/trivialness, and each game is considered by case-by-case basis by the mods.
About the other games you mentioned, note that those rules were added through the years, but the rules don't work retroactively. Games that were accepted in the past may not be accepted today.
Just so you know, a game rejection doesn't have to be final, you can always message the content mods to hear their explanation for the rejection, and discuss the game with them, just be sensible about it.
When submitting games you should also fill the "Additional Information" with as many relevant stuff as you can about that game (like what you just said). It can increase your chances of success (keep in mind that the mods probably don't know anything about your game, and they get about dozens of game requests in a week).
Why is he/she harsh? it is exactly as I told you above. As they said, Iron Snout was accepted 2 years ago, when the rules were less strict. I Just looked at the game, speedruns of 1-2 seconds? you have no idea what is happening on the screen? Definitely won't be accepted now (but the leaderboard will stay on the site anyway).
Also, resubmitting a game won't work, and will just waste the mods time. Either contact the staff for this, or give up.
Edit - also, just note that while your game may or may not be accepted, it doesn't prevent you from speedrunning the game anyway.
If this is the kinda attitude you have in general then you probably should not be doing this kinda thing to begin with. There is plenty of games and communities that do not track their games on the site and even then not even all the categories that people may run because of much of what Oreo has kindly took the time to explain.
The other thing to keep in mind your account is still fairly new as well and that may or may not have some factors on the site staffs verdicts but if a game is that short for a run and there's not a whole lot going on I doubt there will be much there for many people to enjoy about speedrunning the game outside maybe yourself and a few others, which then goes back into the whole note-able reasoning which either way I see it makes logical sense.
No ones gonna keep you from running the game even if its not on the site, technically I speedrun a few other games myself that are not listed here and probably never will be at least any time soon. And either way when talking to site staff directly in a level and calm fashion its very easy to understand and see the reasoning for it.
