Will Sikaflex 291 work for wetsuit repair?

your mum

possibly, but then again so will a stapler.
I would hunt down some aquaseal glue, or ocean and earth and probably a couple of others do neo repair kits with the same glue and some neo patches. this stuff bonds great with neoprene, is strong and relatively easy to work with.

Super glue.
But if you want to use Sikaflex use a soft one like 221 and you will need to use primer 210 I think

Good luck with Sikaflex, I guess it depends on the repair but I've used aquaseal plenty of times, it has been designed for wetsuit repair but I've found even those repairs only last 3 months or so before needing to be redone.......