They say that but they don't really mean it, otherwise they would be claiming Deulofeu's transfer void. Either the interim board is legally able to transfer or they are not, it can't be both, and we know from past experience the interim board has done all kinds of transfers.
The whole debate is absurd and motivated by personal interests. Transfers are subject to a window of opportunity, and can be missed or become more expensive if not done in time. The club's well being and functioning is above any presidential candidates and if a requested transfer is possible during interim board it should be done, specially considering all candidates have confirmed Luis Enrique will continue as manager.
If Luis Enrique wants Deulofeu and Montoya gone, they should be gone as soon as offers come. If he wants Arda Turan signed, then he should be signed as soon as possible, above any candidates cries, some of which have absolutely no chance of winning.
Now this opens a very possible scenario in which Arda ends up at another club when the deal was almost done with Barcelona and he was one of the manager's requests. That would be a great way to start the term by the new president