Personally I would cut the flowering stem out - I want my rhubarb to concentrate on making rhubarb - not new plants. Rhubarb is easy to propagate by dividing it (stick a spade through it in early spring and make sure each new lump has a sprouting bit on the top) so I wouldnt want to risk the seed

Totally agree, chop it off.

just pull the offending stem out , your rhubarb should still produce good stems without the offender