Here's the scenario

Martell v. Stark

Stark has three guys out, Martel has three (one being Red Viper) Mil challenge by Stark (surprise!) two char, two claim, total strength 2 (deadly as well) block with genaric HouseDayne, choose him and paramour as claim. Since House Dayne dude is knelt, but chosen as claim, can he stand to trigger To Be a Viper. The goal was to use the icon removal on final standing Stark character leaving no defense for Red Viper. Say hello to 7 power! (Actually it was 8 since he had Taste for Blood).

Well it would be the same question as for "A Lannister Pays His Debts". Can you use a standing moribund character to pay the cost for ALPHD? Yes you can.

In the same manner, you can stand a moribund character to pay the cost for To Be a Viper.

Huzah! So I did win legitimately!