I think the problem is not enough people want a Gossamer crank to make it worth their while.

There's plenty of other BBs that offer italian-threaded products. Thing is, the Gossamer is at best a mediocre crank, so even though you might eventually be able to source a third-party italian-threaded solution, you have to decide whether it's worth the time and effort. I ran a Gossamer for a couple of years before upgrading to a Shimano 105 and I have no complaints.

My experience with the MegaEVO bottom bracket was that it was reasonably stiff, but it couldn't handle adverse conditions (like winter gravel riding) very well -- after just a couple months of riding it would get stiff and crunchy, despite regular servicing. I replaced a couple and they were higher-priced than I thought they should be, and had the same issue, before I swapped to shimano Hollowtech II and have been running that with no problems for a couple of years.

Sucks that you have to deal with this. Crank/BB compatibility issues are a huge PITA due to the approximately eleventy bajillion different standards.