Presumably he's had a bad case and has not yet fully recovered. Extremely unlikely still testing positive.
Coming back too soon risks myocarditis (as with the ex-Red Sox pitcher, ERod).
Incidence of myocarditis in professional athletes post-Covid is 0.6%
This cross-sectional study compiles data from multiple North American professional sports teams to assess the prevalence of detectable inflammatory heart disease in professional athletes with prior coronavirus disease 2019 infection.
jamanetwork.com