SEP IRA Contribution, Rollover to 401k, Backdoor Roth in the same year?

[401king]

A client has a 401k account and historically has funded a Backdoor Roth IRA (no other IRA balances). This year, he works for another company providing him a SEP IRA contribution. 

May this individual immediately rollover his SEP IRA to his 401k and still be eligible for Backdoor Roth IRAs for 2023 & 2024? He would have no IRA balances at the end/beginning of either year, but I do not know if the SEP contribution eliminates the Backdoor Roth option.