You should do more research then and inform yourself.
I think I am well informed
If you don't think such actions would disrupt the somatic component, that is your perrogative. I think most players would disagree.
Most tables (all I have played on) specifically allow casting while prone or grappled. Further I have never watched a 5E game online that did not allow this.
RAW you can even do somatic components while holding a shield in one hand and an orb or wand or holy symbol or weapon in the other; which would be far more difficult than doing the somatic components in the conditions I mentioned with your hands being free.
When I have seen deviations from RAW it is actually in the opposite direction - allowing concentration while incapacitated or paralyzed, ignoring concentration checks and ignoring spell components and hand switching. Several tables I played on and watched online actually handwaive or ignore handsy stuff completely and make casting a lot easier than it should be (especially when wirelding a shield and weapon). There are even threads on places like Reddit that talk about ignoring hand switching and component rules. On the other hand I have never seen a table make it more difficult than RAW.
Given that I think the number of 5E players who disagree with me is very, very small.
You're assuming the actions described in the spell are the only part of the somatic component. I believe such descriptions are for flare and such more than "this is all it takes, isn't magic easy!!!".
I believe it is generally less than that and when the flare is mentioned it is to point it out.
As I noted above, it is possible to do somatic components while holding something in both hands, because the rules specifically allow for that.
Seriously, though, while you might "see" the weapon, blindingly fast is an expression, but other than the "flash of the blade in the light" there are many very fast weapons, including a claymore. Holding it and moving only your wrists and forearms allow the blade tip to move much quicker.
Not quicker than I can touch my thumbs together and make a fan with my fingers .... and not any quicker than I could "flourish a weapon" .... actually exactly the same amound of time as that if it is a Claymore I am flourishing.