ASADA says it is up to the AFL to decide whether Dyson Heppell's promotion of an Essendon sponsor is appropriate.
Heppell generated plenty of social media comment late on Monday when he tweeted he would attend a local car launch.
The car brand, Kia, is also a major sponsor of the Bombers.
The star midfielder is one of 34 current and past Essendon players who were found guilty of an anti-doping charge.
WADA's successful appeal to the Court of Arbitration for Sport means Heppell, 11 of his teammates and five players at other clubs will miss this season.
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There are strict guidelines around what the banned players can and cannot do during their suspension.
For example, they are allowed to attend AFL games, but cannot go into the Essendon changerooms.
They also cannot be involved in official club activities.
It is understood Heppell has a personal sponsorship with the dealership, which says on its website that the Bombers' star is "part of the team".
"I'll be down at @EssendonKia from 5:30 today for the launch of the new Kia Sportage. Pop over and say g'day and have a squiz at the new rigs," Heppell said in the message.
When told of Heppell's tweet, an AFL spokesman said it was up to ASADA to comment.
An ASADA spokesperson later said: "the sanctions are imposed by the AFL and any enquiries about appropriate activities should be directed to them."
