You can't really have thought this through.
1) The SWP was never in the Labour Party to my knowledge - its IS predecessors may have been, but were never expelled and never campaigned for the Labour Party.
2) The main difference is that the Labour Party was a mass party with decades of existence and years in office behind it, and with hundreds of thousands of members who could knock doors and put up posters and so on. The Labour Party could expel Militant members without a great loss. Respect has slightly over 2,100 members, almost half of whom have signed the SWP's appeal, and - far from expelling anyone - is being split by a faction around George Galloway.
3) There are no entrist organisations in Respect - Respect was always an open alliance between reformists and revolutionaries. The main bulk of campaigners for George and other Respect candidates has always been supplied by the SWP, and they will not be so now. George's skilled media networking and fame will not be enough to beat either Fitzpatrick or Livingstone, and so it seems unlikely that he can win another term.
Your comparison is frankly so ludicrous, so oddball, so estranged from reality, that I can only hope it is an effort at satire.