Ok, so we know that, as per the steps for casting a spell, the CR state that we can indeed cast a Squee that was exiled due to Ixalan's Binding.

However, there is now a Twitter exchange involving Lee Sharpe and Eli Shiffrin where it's been stated that this was NOT the intent; Ixalan's Binding should prevent Squee from being cast. Moreover, both MTG Arena and MTGO go against what the CR says and prevent Squee from being cast; this has been confirmed to be the intended behaviour and not a bug.

(Twitter thread here: https://twitter.com/mtg_lee/status/992087757869596673)

In the same thread, Eli indicates that some sort of change will be coming, but will not release any further info on it.

So, assuming there isn't some sort of emergency change announced tonight, how do we rule on this interaction for the immediate future? Do we continue to go by the CR as they stand, contradicting what has been publicly posted on social media by the Rules Manager, or do we go by the acknowledged intent, going against the CR?

EDIT: Looks like it's been clarified. https://twitter.com/mtg_lee/status/992141022271492096

Edited Chris McGuire (May 3, 2018 03:40:30 PM)

Hi,

While Lee Sharpe is an employee of Wizards and a former judge, he is also not a member of the rules team. And Lee Sharpe has clarified this interaction in a follow-up tweet:

https://twitter.com/mtg_lee/status/992141022271492096

Chatted with Eli. To clarify, current rules ALLOW casting Squee from under Ixalan's Binding. A future update is coming to change this rule. Eli advised the digital teams that, in the interest of not developing it both ways, to implement the change preemptively. #WotCStaff

So yes, the current rules do allow you to cast Squee from exile. There's a potential change in the rules in the future that might change this, but there is no change yet (and there will not be an emergency change - any change would be part of a Comp Rules update that would be associated with an update bulletin that you can see on magicthegathering.com).

Nathan Long
Magic Rules NetRep