Between Raybank and Ostrov LLC a credit

Between Raybank and Ostrov LLC a loan agreement was concluded for a loan in the amount of 50 thousand rubles for 2 months under the guarantee of Omskmebel OJSC. The contract of guarantee provides for the condition that in the event of the borrower failing to fulfill his obligations under the loan agreement, the bank has the right to demand performance in full according to the loan agreement from the guarantor. The bank notified the guarantor that the loan was not returned by the borrower upon the expiration of the loan repayment period. However, the guarantor of the execution of the obligation for the debtor refused, referring to the fact that the loan was not issued on the conditions under which the guarantor undertook to answer, and therefore he is not responsible for his non-return. Is the sponsor´s objection valid?