It's not that they would want to…it's that it is part of the agreement (i.e. a part that favors KRY). The final agreemet will state the exact amount that KRY can request CRRC to purchase.
(d) The A&F Agreement will further provide that following the closing contemplated by the A&F Agreement ("Closing"), CRRC will subscribe for that number of Crystallex’s common shares as is agreed to by the parties at a price per common share equal to the 20-trading day volume weighted average trading price of Crystallex’s common shares on the NYSE-AMEX ending on the date that is 30 days after Closing. The option is exercisable by Crystallex for a period of 30 days following Closing.