For years, SUFC have been on the end of countless criticism about those sales so, while not fully defending the club, I'll try and put a little perspective around it. In the first place yes, the timing couldn't have been worse but in both cases, it was the player who chose to move. The club received offers, those were put to the players and it was their decision. Brian Deane was made aware of an offer from Benfica and in his own words said "what do you do when a club like Benfica come in for you?" In other words, he made the choice.
In Fjortofts case, you have to remember it was a world cup year and given his age, it was his last chance to feature in Norway's squad. In those days, the second division didn't get the coverage it does now and to put himself "in the frame" as it were, he needed to be in the PL. Barnsley offered that opportunity so again, the player made the decision. While he had a decent return of goals at Barnsley, it wasn't enough to get him in the Norway squad but he wasn't to know that when he signed.
There will no doubt be those who still deride the club for allowing the players to leave but there is an argument to say they were doing right by the individuals given the offers made and the ambitions of the players at the time. SUFC had no influence over the timing of the approaches either, it was pure coincidence.