Why is Shadowgrounds allowed?

No, you're not missing anything.

Those are not from a bundle.

The vast majority of the Shadowgrounds keys given away at the moment aren't from any Humble bundle, but from the publisher's Summer Seal, and thus allowed.
(It does not matter if the games were once in a bundle, it matters if the specific key given away now is from a bundle)

Derp Herb

WHYYYYYYY SUMMER WHYYYYYYY
why do you have to exist summer to give me threads like this

summer seal is down, it's not like people gonna get anymore keys

Why is threats like this allowed? So Trine shud be baned to as its a part of HB

imo, the contribution value for the 2 shadowgrounds games should be lowered to 0.01 as you get them for free and ppl kinda abuse it to boost their value.

they said on twitter that summer seal will be back on sunday or so

Just because a game has been at some point in a bundle, it doesn't mean that it is against the rules to post it. As long as your gift is not a key from that bundle, then it is all right.
These giveaways are, or at least should be, against the rules because they are exploited from that seal thing. Will wait for more banhammers.

it look like they are allowed for some people, not for all.
My 2 giveaways got deleted but other ones are still here.

ohlookthisthreadagain.jpg

I have no idea why Shadowgrounds shouldn't be allowed, but Nuclear Dawn, The Ship, Payday The Heist, Sanctum, Faerie Solitaire and other games that were given out for free should.

I think they're letting it slide on this one as they work on that new system which will automatically remove and suspend anyone who is breaching the bundle rule. I remember Yatterman mention that in some random threat anyway.

So I guess it's allowed for now, but don't be surprised if in the future the contributor money you gained will be reset.

You answered your own question. It WAS part of a bundle. Now it's not. The individual games are allowed when the bundle is no longer on sale.

Additionally, the individual keys from the bundle are never supposed to be given out.

All of this is in the FAQ. I suggest (re-)reading it.

Shadowgrounds is neither of these situations. The keys were obtained in another manner, and the game is not currently in a bundle.

Steam sells Shadowgrounds in their store therefore it is allowed. When is was part of the bundle, there was no separate key. And just because the developer decides to give away a bunch of Steam redeemable keys does not mean it should be banned either.