The 21-year-old is out of contract at Fremantle at season's end and at 206cm would be an attractive proposition for opposition clubs desperate to bolster their ruck divisions.
Matthew Warnock, 24, says he has talked "a little bit" with his younger sibling about coming home.
"All we can do is wait until the end of the year and work it all out then," Warnock said.
"He'd like to be in the Freo side at the moment, but he's not, so he'll work it out at the end of the year and figure it all out then."
Warnock said he was "pretty close" with Robert and they "speak quite a bit" about life in the AFL.
"It's good to have someone in the system to compare notes and have a chat about how we're both going. We get a bit of feedback off each other and we help each other out when we can," Warnock said.
As for Robert's height, Matthew (who also stands at 192cm) says the paternal side of the family are the culprits.
"Dad is about six [feet] four and my uncle is about six [feet] six, so our height comes from that side [of the family]," Warnock said.
"But there is no one else in the family the size of Robert."
