Suicide (or robotic) boats are vulnerable even to simple machine gun fire. A single .50 caliber (12.7mm) API round will touch off the explosive charge. That's just small-scale, pedestal-mounted weapons, and ignores CWIS, attack helicopters, picket craft, patrolling Super Hornets, etc.
They travel at 40 to 50 knots maximum. Even in WW2, the Kamikaze had a slight "speed advatage" to put it mildly.
The biggest thing I think people are forgetting would be the location of the U.S. fleet. It's not going to steam through the straights into the Persian Gulf, presenting a fat, broad-side target into a tight, 100 meter deep sea; the CBG will be located in blue water. Range... these Iranian boats will have neither the range, nor even the ability, to traverse 200 nm of blue water. Look at a simple map of the area:
A CBG could patrol the ocean either closer to the Pakistan shoreline, the Gulf of Oman, or near the Omani city of Masirah... if hostilities erupt, the Omani land mass would shield vessels from radar, and the Hormuz straights (and Iranian assets) are easily within range of the CBG assets.
This notion of suicide boats reminds me of the Iranian flying boat program:
Said to be "stealth" despite the huge, exposed engine and what looks to be a radiator. With a payload of probably 50 kilos.
I am a member of Iran Defense, and am enthusiastic and hopeful that so much of the past can be put behind both countries, as there is much that is praiseworthy about Iran.