Nothing says you have to limit it, but I think for your ongoing sanity and social life it's worth giving her a 30-45 min window? If she gets in the habit of spending 2 hr eating then that's 6 hours out of your day, and I'm sure there'll be days when you'll need to go out after lunch. BLW is partly about our DCs learning normal table manners etc, and while we might spend 2 hr at the table for a Christmas lunch or something it's not what we'd do on a normal day.
I mostly eat breakfast and lunch with DD (7 months). When I'm finished eating, I busy myself in the kitchen for a bit while she continues to play with her food eat. It's about 30 min all in.