Urgot's Ult vs Morgana's Shield

So I'd come across this in my last match. With the enemy Darius low, I'd ulted him, his health well within the range. However, the moment Morgana shields him, my ult proc does nothing, and it's forced into its cool down. Now due to the effect of how the execute works, I can see how the game's programming would declare it as something that Morgana's shield can stop. But since the purpose of this ultimate is to execute, and not specifically disable/cc, I'm unsure of how I feel about this.

Opinions?