Question about frozen ball foul


New member
I'm not allowed to post links yet, so I can't post the youtube video about which I'm asking. But the match video is:
Shayne Morrow vs Bucky Souvanthong at the Valley Forge Bar Box

at 23:16,

a foul is called... I don't understand why. The cue ball hits the bottom rail after hitting the frozen 2. Doesn't this make it a legal shot? Appreciate any info. Thanks.