Originally Posted by golfmad

they
T͟Hā
pronoun
1.
used to refer to two or more people or things previously mentioned or easily identified.
"the two men could get life sentences if they are convicted"
informal
a group of people in authority regarded collectively.
"they cut my water off"
2.
used to refer to a person of unspecified sex.
"ask someone if they could help"

You could get away referring to a fellow poster under option 2 but not really with option 1 but it doesn't really matter.