Space... Without the arm for the mk13 launcher, the OHP has no way of firing AShM or SAMs. It could get a mk41 or sylver vls launcher in front of the mk13 but thatwouls likely only support SAMs. AShM either need the mk13 to be operational, or boxes/encapsulated launchers...hence PN placed those on Alamghir and only space suitable is in front of the bridge.
As to why its in Russia, when you hear hoof beats think horses... Not zebras. Most common reasons for visits are good will missions or exercises. There would be no reason to send Mi35 via a military ship of this type... And only 2 would fit. Those are sent on freighters or airlifted by strategic lift aircraft. Same goes with other weapons like SAMs of which there is no known sale.
Only major intersting thing is that PN sent an American vessel and that these exercises were unannounced ahead of time.