No issue
The astroturf is already used on various circuits:-
SPA FRANCORCHAMPS (BELGIUM)
-MONZA (ITALY)
-HUNGARORING (HUNGARY)
-SILVERSTONE (UNITED KINGDOM)
-BARCELONA (SPAIN)
-ALCANIZ (SPAIN)
-NAVARRA (SPAIN)
-INTERLAGOS (BRAZIL)
-ABU DHABI (UAE)
and is fully FIA approved for use.
If its installed correctly, there should be no problem with it. The astroturf will actualy drain/dry better than normal grass and the matting should prevent rutting by having better displacement of weight.
Surely keeping the car on track during the wet is more of a concern than the parts that are not on the tarmac?
My gardens got astroturf and is already dry, following this mornings rain
next doors grass is still soggy!!!