What's to stop Iran from using the threat of cutting those cables as leverage? A speedboat and a depth charge are all it takes, and neither are particularly difficult to make.
The threat of force is much more potent than the actual use of force: this has been the delicate dance that the US has used with Iran since the Revolution.
It took an idiot to try and actually use the full force of the USAF against Iran and reveal that the force was manageable- not great, but not going to topple the regime. And once that force was used and Iran's leaders realized it could be survived, that threat became much weaker, forcing a decision onto that previously mentioned idiot, he could either escalate to use greater force (some form of ground troops) or admit that he made a mistake and lost a war. And I suspect that the same will be true for Iran: the threat of cutting those cables is far more potent than the actual effects of cutting the cables.
The Internet is, it turns out, pretty good at routing around damage. The Russians have done some cable cutting in the Baltic Sea and it is annoying but it is not a winning move.
> The enormous pile of ordnance floating in the gulf of oman that can be easily dropped on Tehran, for one
Probably not. The other comment is right: cutting cables means having its own cables cut. (Tehran is also probably weighing whether it wants to continue mobilising almost all of its neighbors against itself. Trashing e.g. Kuwait for shits and giggles isn't strategically productive.)
> might be a good time for some good old-fashioned false-flag action
It's always "a good time for some good old-fashioned false-flag action" if you can pull it off. Given Riyadh and Abu Dhabi are already bombing Iran, and are now unaligned, there wouldn't be much for the U.S. to gain from something like this. (And if Israel were to pull off a false-flag operation against the U.S. now isn't better or worse than tomorrow or yesterday.)