The Sardinian club's president, Massimo Cellino, remains in custody at Buoncammino prison as police continue to investigate alleged attempted embezzlement and fraudulent misrepresentation surrounding the unfinished stadium, where Cagliari have struggled to host home games throughout the season.
It is reported in Italy that Cellino only used temporary permits to build the16,200-seater stadium in Quartu Sant'Elena while involving mayor Mauro Contini - who is also under arrest - in allegedly misappropriating council funds to help finance the construction.
La Nuova Sardegna newspaper suggested the Is Arenas, which lies close to the Montelargius national park, could even face demolition but Grassani is urging caution.
He told the Corriere dello Sport: "In terms of president Cellino's case I am only involved with the aspects relating to the Is Arenas, but I am sure the president will come out of this clean.
"Unfortunately it's difficult to build new stadia in Italy. The buildings are 99 per cent public buildings and modernising or building a private structure is not simple.
"Cellino has tried to do so in via crucis as he has had to fight against bureaucracy.
"If Cagliari cannot complete the last leg of the season at the Is Arenas it will be a defeat for all of sport and demolishing the structure would be a mistake.
"I am convinced that Cellino will succeed in proving that he is not involved in this matter. The president's legal representatives are making a request for him to be released today."
Cagliari's struggle against the authorities first became apparent when the Lega Serie A ordered the club to host Serie A rivals Roma behind closed doors in September.
Cellino instead defied the order and invited season-ticket holders to attend regardless, forcing the abandonment of the fixture as Roma were awarded a 3-0 walkover victory.
The club's initial appeal against that punishment was rejected but Grassani revealed how Cellino, prior to his arrest on Friday, had made significant progress in his crusade to reorganise the game.
He added: "Cellino's original appeals to the local administrative court have been accepted but a final decision on the matter must be taken soon so as not to distort the championship."
Cagliari left their previous Stadio Sant'Elia base during the final weeks of the 2011-12 season and played their remaining home games over 650 miles away at the Stadio Nereo Rocco in Trieste.
Following the Roma debacle, a home match against Juventus was moved to Parma's Stadio Ennio Tardini in December.
The Lega recently ordered Cagliari to host AC Milan at the Stadio Olimpico in Turin, with the Sardinian club successfully appealing against the decision, but it remains to be seen whether the Is Arenas will be cleared to host Torino on Sunday.