Personally, I don't consider it to be rude to "not search", nor rude to "suggest a search".

On "not searching" -- what's rude is not doing anything to help your own quest for the information. Reading the recent topics in the relevant parts of the forums, paying attention to the forums over time, thinking about what you've seen -- those indicate that you've put some effort in to it before you asked ... and that's what makes it not rude. Doing a search is just one element of that effort, and it's not a mandatory element. (sometimes I search, sometimes I go by memory and/or observation)

On "suggesting a search" -- it's a relevant answer to a question. You can word it in a rude way, you can word it in a matter-of-fact-way, or you can word it in a polite way. As long as its not the one of the three that is the rude one, I don't have a problem with it.