Dear Sandhya,
You have asked for the draft and a learned member sent the draft also. However, the question arises is if the employee did not report for work, then who signed the attendance register on his behalf? Does this person not merit the issue of the warning letter? Signing as a proxy should also be considered misconduct.
By the way, who discovered the absence of the employee at the workplace, how it was discovered and who reported the absence to the authorities concerned? If the report did not come through formal communication, then the Supervisor or Manager on duty also needs to be asked for an explanation for their failure to highlight the proxy signature.
I recommend you look at the incident from all angles instead of just attributing the default to a person.
Thanks,
Dinesh Divekar