But all this changed last spring when Mr Arafat, from his rump mini-state in Gaza, decided to recover his influence as PLO leader in Lebanon and reopen all his guerrilla offices in the great refugee camp of Ein el-Helweh outside Sidon, pay his former officers again and send his armed fighters marching through the camp.
Now comes the death sentence - in absentia - against Mr Aboul Aynain from the Lebanese military tribunal for "forming armed bands with the intention of committing crimes against civilians and attacking the Lebanese state".
What is unclear is whether the "crimes" are supposed to have been committed during the 1975-1990 civil war when more than 150,000 were killed, or in the past nine years when Palestinians have been accused (without much proof) of killings in the Sidon area.
Already, PLO officials in Gaza are accusing the Leb-anese of a "political" sentence against their representative in southern Lebanon, prompted by Mr Arafat's decision to re-exert his power in the Palestinian camps there.
Until six months ago, the 60,000 population of Ein el- Helweh camp was ruled by anti-Arafat Palestinians, most of whom were supported by Syria and who regarded the 1993 Oslo agreement as a betrayal of the Palestinian refugees in Lebanon. The majority of the families come from that part of Palestine which became Israel in 1948.
Refugees will be discussed in the Palestinian-Israeli final status talks. Israel has already refused to contemplate the return of 1948 refugees or their descendants - numbering perhaps three million; and since the Oslo accords, Mr Arafat had studiously ignored the 350,000 Palestinians who fought for him at such cost in the Lebanese war.
But now, anxious to show he has a "card" in Lebanon - because control of the Palestinians there will give him greater influence in the final negotiations with Israel - the PLO chairman sent Mr Aboul Aynain to Ein el-Helweh to reorganise his guerrilla force. A week ago, armed Fatah staged a rally in Ein el-Helweh for the first time in a decade.
Which might have been Aboul Aynain's undoing. For the Lebanese wish to control the Palestinians in Lebanon. And although under the 1969 Cairo agreement, the Lebanese allowed them to carry arms in their camps, the Beirut government has insisted several times this year that Palestinian refugees will not be allowed to stay in Lebanon.
And Syria, which has 22,000 troops in Lebanon and whose " sisterly" accords with Beirut give her dominance over Lebanon's government, may have its own uses for the Palestinian refugee guerrilla fighters.
If Israel withdraws from southern Lebanon without retreating from Golan, then those Palestinian guerrillas in Ein el-Helweh could be as valuable a "card" for President Assad of Syria as for Mr Arafat in Gaza.
Mr Aboul Aynain is sitting tight in the little concrete office he runs in the Rashidiyeh camp. "We regret that Fatah should now be regarded as an "armed band" when we have always respected the sovereignty of Lebanon and its laws and refuse to compromise its security," he says. "I don't think I'm going to hand myself over."