That is fine.
If our team hadn't undergone such big changes already over the last 2 years, I'd sell him too for a ridiculous offer... But I am not a fan of unnecessary turnover, especially of a team that has been in flux for two years. I wouldn't have sold Vidal 2 years ago, and I wouldn't sell Sandro now. If Sandro was 28-29, and we had a stable team built over several years, by all means sell him for a ridiculous offer. But right now, with the state of flux our team has been in for 2 years, regardless of how fantastic the results have been, it's time to consolidate and build on those results, by not selling again this summer. Next summer, or perhaps the one after... different story. But this summer is 100% no.