The "3000 pounds" is not actually in the proposal and should be ignored. "250 knots" is a just in case for aircraft manufactured under the "LSA" rules and not a limitation on sport pilots.
The actual proposed "What you can fly under S.P. rules":
61.316 What are the performance limits and design requirements for the aircraft
that a sport pilot may operate?
(a) If you hold a sport pilot certificate, you may act as pilot in command of an
aircraft that, since its original certification, meets the following requirements:
(1) A maximum stalling speed or minimum steady flight speed without the use of
lift-enhancing devices (VS1) of not more than 45 knots CAS, except for airplanes, which
must have a VS1 speed of not more than 54 knots CAS at the aircraft’s maximum
certificated takeoff weight and most critical center of gravity.
(2) A maximum seating capacity of two persons, except for airplanes, which may
have a maximum seating capacity of four persons.
(3) A non-pressurized cabin, if equipped with a cabin.
(4) For powered aircraft other than powered gilders, a fixed or ground-adjustable
propeller, except as provided in paragraph (b) of this section.
(5) For powered gliders, a fixed or feathering propeller system.
(6) For gyroplanes, a fixed-pitch, semi-rigid, teetering, two-blade rotor system.
(7) For powered aircraft other than balloons or airships, the loss of partial power
would not adversely affect directional control of the aircraft and the aircraft design must
allow the pilot the capability of establishing a controlled descent in the event of a partial
or total powerplant failure.
(8) For helicopters, they must be certificated with the simplified flight controls
design and designation.
(9) For a glider, fixed or retractable landing gear.
(10) For an aircraft intended for operation on water, fixed or retractable landing
gear or a hull.
(11) For powered-aircraft other than a glider or an aircraft intended for operation
on water, fixed landing gear except as provided in paragraph (b) of this section.
(b) If you hold a sport pilot certificate, you may act as pilot in command of an
airplane that, since its original certification, has retractable landing gear or a controllable
pitch propeller if you have met the training and endorsement requirements specified in
§ 61.331