I'd be more concerned with with sucking up abrasive debris into my raw water pump. The story in the OP also mentioned that a sailboat had gotten debris wedged into there rudder and causing it to jam.
Boats differ, of course, but those pics looked like a couple of inches debris at the most. The raw water intake should be lower than that*, plus you have (usually) at least two levels of straining before the heat exchanger. Most sailboats (as I'm sure you know, but for the benefit of others) have large rudders with the top at or near the waterline. Much easier to get something jammed between the top of the rudder and the hull then powerboat rudders, which tend to be deeper and with more space around them.
That said, standard practice for something like that (if you can't skip it) is to slow down (not a problem on a sail boat) and kinda coast straight through. Most of the time you'll be fine. I bet they were swinging their rudder back and forth (or didn't disable the autopilot) and that's what got it jammed.
*At normal draft, my main seachest is at about 10ft below the waterline. We suck stuff up pretty frequently, but just clean the strainers. An ocean going vessel, even a small one, should have a duplex strainer on anything important so if you clog it, you just switch to the other side and keep trucking while the first one gets cleaned. I was hanging out in a river once that was so silty, the strainers were clogging as fast as you could clean them, so the snipes were down there just constantly rotating clean, switch, clean, switch. Long day for them.
