Gideon and "must attack X" cards

[Phoenix Ignition]

I was playing MTGO and am wondering if this is in the rules or just a bug.

The opponent played Gideon Jura and used the +2 ability. I had a Geist of Saint Traft in play and therefore attacked Gideon with it the next turn, but it gave me the option to use the 4/4 angel token to attack Gideon or to directly attack the player if I chose. What rules knowledge should I know for this interaction? Without going into specific rules I would have just assumed the angel must attack Gideon.

MTGO is known for bugs involving their rules interactions, however.

Thanks.

[Barook]

It's fine since Geist attacks due to Gideon's trigger. The token is created afterwards already attacking, so it isn't affected by Gideon anymore.

[cdr]

Gideon's ability is a requirement on declaring attackers (508.1d (http://www.yawgatog.com/resources/magic-rules/#R5081d)). There's two concepts called restrictions and requirements, and they only apply to declaring attackers and blockers. Since the angel is put on the battlefield attacking, it isn't involved in declare attackers and doesn't care about restrictions or requirments.