I already cleaned mine up so I can't post a picture. You can look at the photos on page 7 of your knock sensor DIY. There are a couple of photos there in which you can see the stuff under and around the water bypass hose.
Although mine didn't look like a rat's nest, just lots of calcification stuck to the cylinder head and around the knock sensors.
I was unable to see the picture you mentioned. It is highly advised to use post# instead of page number.
If it is coolant crusted over, it points to a leak. When leaks are minor they crust over and seal the leak. By scraping it, you may have opened up the leak. In situation like these it is highly advised to replace the hose or leave it alone. Now if it was battery post then by all means wire brush it and give it a coat of terminal grease.
check the water pump, is it time to replace, I have same issue but it gone after I replace the new water pump and timing belt! Also, clean the Mass Air Flow sensor with cleaner , when I was replace the knock sensor last year! good luck!