The Serbia international, 21, has joined the Bluebirds until the end of the current campaign and Warnock has no problems with the unusual nature of the agreement.
“It’s quite acceptable. I think it’s a good deal for both parties because I want to play him,” said Warnock.
“I’m not signing him to make the numbers up. He’s a good lad and a good player. All of our scouts have recommended him to us.”
Grujic has played six games for the Reds this season and Liverpool manager Jurgen Klopp is keen for him to experience more first-team football.
“I think we can be good for him. I think we can get him match-fit. There’s a World Cup this summer, and he has ambitions to go to that. So if we can get him up and running, that will be great for both parties,” Warnock added.
“We won’t get punished if he gets injured and things like that. We’ve got 19 league games and hopefully he’ll play in all of them.
“A lot of clubs take players from the Premier League and don’t play them. Well that’s a waste of time. Same as me sending someone out – if they make up the numbers it’s pointless.
“We’ll have to look at penalising clubs if they don’t play them for a percentage of games. Jurgen really likes the lad and he wants him to continue his education. And he just wants to come and play.”
Newcastle have been linked with a shock move for former Sunderland goalkeeper Simon Mignolet during the summer.