Liverpool will travel to Hoffenheim for the first leg of their Champions League playoff on Tuesday night, before welcoming the Bundesliga outfit to Anfield next week.
Coutinho will again be absent due to a reported back problem, although it is thought that the Brazilian does not want to play after reportedly handing in a transfer request amid interest from Barcelona.
Thompson has claimed that Liverpool could keep Coutinho if they made the group stage of the Champions League, but would understand if the playmaker was sold if Hoffenheim triumphed over two legs.
"I think the outcome of the playoff could have a knock-on to Coutinho; if things go pear-shaped then has a pretty good excuse to say, 'Let me go, I want to play in the Champions League', so it is even more important in that respect," Thompson told Sky Sports News.
"If we get through to the group stages then I think the owners - because they put everything at Coutinho's disposal before, giving him a five-year deal and the pay increase that he and his agent asked for - have strong enough grounds to stand firm.
"The owners know it's Barcelona but to them it's a contract signed and until they've got a player who can fill his boots then they have no interest in selling, especially after the way the club was embarrassed with the timing of the transfer request."
Liverpool owners Fenway Sports Group recently insisted that Coutinho would not be leaving Anfield this summer.