[blub]

I agree with your comment, except the last part. This feel free to do X is just a covert agressive response, not unlike feel free to submit a patch.

When I get that from a project where I report a problem I immediately think "feel free to keep your buggy docs/code".

A straight but assertive answer is IMO much better: "we don't have time to do X, could you please help?" or "we have higher pririty bugs that we need to work on, but we could sure use your help if you have some time". Heck, even "let's take 1h and work on improving it together" would work for me.

Bottom line is that unless there's a clear responsibility involved, other people don't have to perform certain tasks, so they should be politely asked for help...