Here is the trickier part: there is nothing in the rules that says that a bound delegate must sign the statement of support for the candidate to whom they are bound. The only thing they are bound to do is to VOTE for that candidate for the number of ballots specified by their state. They are not required to support the candidate in any other way, whether that be voting for rules, delegate challenges or signing a statement of support for the nomination.
(2) For any manner of binding or allocating delegates under these rules, if a delegate (i) casts a vote for a presidential candidate at the national convention inconsistent with the delegate’s obligation under state law or state party rule, (ii) nominates or demonstrates support under Rule No. 40 for a presidential candidate other than the one to whom the delegate is bound or allocated under state law or state party rule, or (iii) fails in some other way to carry out the delegate’s affirmative duty under state law or state party rule to cast a vote at the national convention for a particular presidential candidate, the delegate shall be deemed to have concurrently resigned as a delegate and the delegate’s improper vote or nomination shall be null and void. Thereafter the secretary of the convention shall record the delegate’s vote or nomination in accordance with the delegate’s obligation under state law or state party rule. This subsection does not apply to delegates who are bound to a candidate who has withdrawn his or her candidacy, suspended or terminated his or her campaign, or publicly released his or her delegates.
The only way is for Cruz to drop out, and then the states Cruz won conspire with the GOPe to support a white knight, as only Cruz has enough wins to reach the 8 state threshold of free delegates.
-PJ