Striker Icardi was stripped of his captaincy in February after comments from his wife and agent Wanda Nara were said to have riled club officials.
While Inter did struggle at times in Icardi's absence which saw their Europa League campaign ended and their top four hopes risked, the club has since rebounded and now sit third in the table.
Speaking ahead of that game, which presents Inter with a chance to avenge their 4-1 loss in the reverse fixture, Spalletti told reporters: "The Icardi issue was an opportunity to re-evaluate that Inter are a team and not a single player.
"As I said many times, there are moments during the season when you have to analyse things more carefully.
"We must try to be authentic and not timid. Be clear, be yourself. Do what is best in that moment for these club colours."
The club's Curva Nord supporters are set to protest Icardi's ongoing employment at San Siro, having released a statement denouncing the 26-year-old in which they claim he "dug his own grave".
Spalletti did not outright disagree with their sentiments, but hopes the fans will get behind their team on Sunday.
"Inter belongs to those who love it and above all those who actively participate in supporting it," he said.
"I am convinced that those who have Inter in their heart will know how to behave and work to help the team get a result."
Inter sit on 56 points, four points ahead of local rivals AC Milan in fourth, and perhaps most importantly, five ahead Atalanta in fifth.
A victory this weekend would see Inter move eight points clear of Atalanta and close in on a top-four finish with just seven games remaining.