There are so many places we all go that involve having many people in a tight location that this really falls on each of us to decide where we are comfortable.
Full movie theater, concerts, amusement parks, wide array of sporting events, church, airports, graduations, crowded beaches, clubs, department stores, subways ............. and we have seen some of those places affected.
Disney has LOTS of security specialists, many that are very highly qualified to plan and watch. They have plans for lots of things. My DD worked at Disney Springs and one of her managers was a very highly trained security person who worked in DC who assured her (at a time when there were threats made) that there are detailed plans for everything. Am sure they have doodled every possibility, and likely will find lots of holes in your plan - if they even look at it. You would have been better off with short and sweet that you are concerned with the bottlenecks at the parks. But am sure you will get a call or email to tell you you've been heard and they appreciate your concerns.
Bottom line if you are not comfortable with the crowds and/or security at the peak times - then enter the parks off peak times, book PPO dining reservations, use alternative entrances etc. My DS has anxiety issues so we often adjust our plan around peak and have found that even when many are still heading it only takes us a few minutes to go through.
The further away from the parks that they can institute safety checks, the better. For those staying at the resorts, a full check at the bus loading stations at the resort would be best. Then once they get to the parks, they get expedited entry. Monorail, bus, boat...full safety check before they get on. AK/HS/Epcot..check non-bus guest at an entry point from the parking lot.
Basically do it at least 100 yards from the park entrance in a manner that produces as small of a congregation as possible.
Don't agree. The more space you leave between security check points and entry, the more opportunity there is to gain entry or get something in from another person. It creates a security gap. They are still adjusting and finding the best solution, and we just have to work with it whether that means planning extra time, entering non-peak etc.