C.f. https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/thread/AKVB363GFCHHJ5MTHGVYHYT6NLLTF5VM/
webkitgtk is used by gnucash to render charts on account data that come from goffice. gnucash is a gtk2 app... moving to a newer webkitgtk is not going to happen until gnucash moves to gtk3, which may never happen.
I understand that webkitgtk is insecure. However, webkitgtk is not used in gnucash to render content remotely from the network. To exploit whatever insecurities that this may have, the process for the attack would be:
Even if this is theoretically possible, I would find it far-fetched.
Ergo, asking for a bundling exception, per the above referenced thread.
You don't need an exception anymore. Just put Provides: bundled(webkitgtk) = version in your spec file and be on your way. A comment explaining it (ideally with an upstream bug report) would be terrific.