Normally yes it would but since the sub out only has bass content it you connect it a 2,1 speaker you should only hear the .1 part of it playing. If the input for the 2.1 is on the sub you may not even have to connect the satellites at all.
The subwoofer output of the soundbar might be a mono 3.5mm jack and the 2,1 speaker input would be a stereo jack so you may need an unusual cable to get them working. If you have the original cable that came with the soundbar to connect the sub that would indicate if it was mono (1 black band for mono or 2 black bands for stereo on the plug.)