F2Pool is just messing around. Now they are indeed signalling support for SegWit, but for how long? It won't surprise me a single bit to see them change from opinion after a while. If you have been following tweets coming from Mr Chun for a while, you know exactly what I am referring to. For those that don't know, please browse through his Twitter history --
https://twitter.com/f2pool_wangchun