Petition filing for FY21


I am selected through lottery as informed by my employer in this year lottery system but as Covid-19 situation getting worse, they are holding up my petition filing.
Just would like to know if they can really do so?
does USCIS allows employer to not to file after lottery selection? Do they fine employer for abusing the system this way?

I don’t think there is any law which forces the employer to file the petition after you got thru the lottery. Its up to the employer if they have second thoughts.

Thanks @Cheraz_Bharucha for the input. Any idea as how 90-days petition filing window works?
As hard copies of petition documents needs to be mail to USCIS center in USA, so the courier should reach USCIS well before 90-days and/or it should get acknowledge by them with receipt number before 90-days expire OR courier-in-transit time does get counted post 30th June?