The Indycar innercircle is maybe 50 people or so. I think Panther racing is even based in Indianapolis. These guys see eachother every week and probably around town too. If Randy had a beef with John Bernard, couldn't he just hop around the block to the Panthershop and talk it out like grownups?
The comparison with NFL and the likes is moot because in the NFL there are thousands of players, coaches, team owners and staff, based all over the country. Indycar on the other hand is maybe a core of 50 people that have known eachother for 15 years and often much longer. With that kind of personal connection, giving a big fine for one tweet is harsh and to me rather offensive.