Whilst any problem with the keel attachment to the hull is a serious matter not to be taken lightly, I have to say that I would be inclined to ask your insurance company surveyor to provide specific information to back up his assertion that this is a "typical problem with Bavarias." Also a question to ask your insurer is what basis has their surveyor used in order to make such comment.
I am no expert in regard to Bavaria boats, but there is an awful lot of rumourmongering on various subjects which if repeated often enough can result in those gullible enough to believe those rumours being sucked into believing them to be truth rather than rumour. One of my neighbours who owns a Beneteaux used to rib me with tales of Bavaria keels falling off, but to my knowledge I have heard of only one definite and one possible loss of a keel from a Bavaria boat. The one that lost its keel was known to have run aground quite forcibly.
My neighbour has had less to say about keels coming off since the Cheeki Rafiki incident where that boat was, if I remember correctly, built by Jeanneau which I understand is part of the Beneteau/Jeanneau group, and had suffered several groundings during its lifetime.
Bavaria themselves may be reluctant to provide definitive information, but they might be prepared to dispute any rumour that tarnishes their reputation.
For what it's worth, my boat is a 2002 Bavaria 36, and neither I or the yards that have lifted my boat out over the last seven years have ever commented about the security of its keel, and I have seen nothing that might give me any cause for concern.
The best source of information about Bavaria boats is surely the Bavaria Forums with this forum being the best of the lot. I've read most if not all of the various threads within this forum, and while there have been occasional queries regarding keels, they don't exactly leap out as being a problem area, far less something that could be described as a "Typical problem with Bavarias."
Please keep us posted in regard to how you get on with your insurer, and out of interest I'm sure that most of us would like to know who your insurer is, as much as anything on who to avoid insuring with in the future, and the surveyor too unless they both come up with good reasons for such statement.
I suppose arguably too, there is a question to ask your insurer why they accepted your premium without warning you of a problem that they think is "Typical of a Bavaria." Indeed if it is a Typical Problem, why is it not specifically excluded within their terms and conditions.