As you've surmised this is being blocked by our L7 protection that is used for a number of things including blocking your usual attack vectors (XSS, SQLi, DDoS, etc). Unfortunately it is done using some heuristics that attempt determine whether query strings match with common signatures, and so tuning it is a bit of an iterative process.
We're aware that our userbase are, on average, more technically savvy than most, and this is a bit of a tricky thing to balance. Allowing users to search for code snippets that may form parts of previously identified XSS attacks while also ensuring that they aren't providing a vulnerability can be tricky - we employ a defence in depth approach here as a result - L7 WAF as well as sanitising inputs.
I've tracked down the specific signature that these queries triggered on and done some work to improve on it. You shouldn't see this type of search query getting blocked. Thanks for the feedback, and please, make sure you continue to provide feedback like this, as it allows us to re-evaluate the heuristics we are using and tune these components to provide better UX without compromising security.