I am a little late to the party but a couple of observations. I think age is an important factor. If there is a woman donor in her 80s who wants to meet and have dinner with a 35 y/o male principl dancer , and a donation may be associated with that, then I don't think there is too much wrong with that picture. If, however, it was a fifty year old donor who wants to meet all of the new 18 y/o corps dancers - well, that would be pretty suspect to me, and I think the company has an obligation not to put their dancers in that situation.
I think there just has to be a little judgement. First , most men and women dancers in their thirties are pretty sharp socially, and I don't think they either want or need protecting from big brother. Heck, it is probably the donors that need protecting from them.
Second, there are plenty of opportunities to socialize with the company members , whether its backstage, at talks, at fund raisers etc. , I have a mailbox full of these type of invitations, and I don't see too much wrong in paying to go to a fundraiser etc. but trust me, these events can be just as stressful for the donors as the dancers!
But third, I think that just because you have turned 18 you haven't necessarily become a man or a woman who is capable of handling delicate social/work/donation situations. I would have a real problem with a 18 year old corps member being expected to have private or semi-private dinner dates with donors. However, it would be my expectation that the older principals interact socially with the key donors -and that can certainly be discussed at a contractual level with them each individually . My hope is that the trustees or board provide sufficient oversight to avoid conflicts.
( By the way, I believe the Yankees baseball players have certain contractually obligated social and charity obligations, but perhaps after the first first 10 million or so a year the bar can be raised a little!

)