Datapoint:

I opened a new United MP account for Mrs. akcae (she didn't have one yet, gasp!) and transferred 1000 UR points. Then I used the link provided and got the 60K miles offer. Applied her for the card, got "reviewing the application" message, which wasn't surprising, since she already had 4 other Chase cards. This was three days ago. This morning when I logged into her Chase online account, I noticed that she was approved, albeit with a minuscule ($1000) credit limit, so this probably isn't even a Signature card. I sent a SM asking for a portion of another card's line, which she never uses, to be moved to this card to bump it over $5000. Not sure if this can be done via SM, but worth a try.

Hopefully this doesn't affect the sign-up bonus. Will report when miles post.