At least here "travel insurance" generally means insurance that covers things such as:
Travel delays
Lost baggage,
Cancellation
Medical expenses when abroad.
The first three don't really apply to a GA trip, though they could apply to a trip to the US (for example) on an airline, and you then do some flying while in the US. Delays on your commerical flights would be covered, but they aren't going to play for an extra night in a hotel because the weather wasn't VFR.
That leaves medical expenses as the big one left.
A "travel insurance" policy, wouldn't generally cover any damage involved to the aircraft or third parties.
If you read the wording on the policies carefully you see that they generally have a defination for an insurance trip. The one I have (which doesn't cover private flying) requires a journed of more than 150km and at least 2 night booked accomodation or some sort of public transport tickets proving the journey.
In relation to the private flying they usually say that certain parts of the policy won't pay out for claims in relation to these activities. So if you do some flying while on holiday, and then you return airline loses your baggage, you can still claim on that.
dp