Which makes no sense afterall because they anyways have limited online race time, so why we cant drive arcade mode in the spare time ? Oh well...
Then deactivate it during online races that people are forced to race online. But the rest of the day it should be accesable... well lets see !
From what I read the races will run daily at the set times :-
"Beta racing schedule
Hosting of race events starting 15 April | 13:00 UTC / 14:00 BST / 15:00 CEST
During the weekend
Race Hours | 15:00-18:00 UTC / 16:00-19:00 BST / 17:00-20:00 CEST
During the weekdays
Race Hours | 17:00 – 20:00 UTC / 18:00-21:00 BST / 19:00-22:00 CEST
We look forward to seeing you all in the beta this weekend!"
You will be able to qualify your times in TT before the races (I can't see this being limited in time too much) so from Late Fri/Sat every day you should be at least be able to play a TT even if you miss the race or get on the new tracks available to try them out. They said they are giving the codes out now so everyone can download it and it was not all done on the sat etc and bear with them until the weekend 👍
p.s UTC = GMT