It's a crap idea. If patents could not be transferred, then if person X worked for company Y, and then went to company Z, they'd be taking the patents with them with no means to leave them with the company that was using them.
You need to read what I said a bit better. Of course they can be assigned to the original company who funded the work (i.e. the employer of the inventor(s).
company X can buy company Y and then give themselves free licensing rights and have their legal team take over suing others just as companies do now
If a company completely *buys* another company, in effect it is now that company. But that would SIGNIFICANTLY cut down on patent trolls (the whole point of this) as it would make it a much more expensive, complex, and risky undertaking. For example. Google did buy Motorola, keep most of the patent rights, and sell of the rest - but it cost them MANY billions of dollars to do that (and luckily Google was just doing it defensively, though of course they could assert them).
Regardless, one could still assign full rights to manage said patent portfolio to some 3rd party company. That would be nearly impossible to avoid - just consider the 3rd party as a bunch of lawyers and have them do all the same stuff those 3rd parties are doing today, simply leaving the actual patent assignment where it was.
Why is it impossible to avoid? As part of not being able to sell/permanently assign the patents to that 3rd party company (i.e. the troll), it follows that only the original owner can actually sue for infringement. Again, the idea was trying to prevent patent trolls, not patents.
And OBVIOUSLY it was all just a suggestion. No off the cuff 2 paragraph statement is going to solve patent trolling. But making it harder for the trolls to acquire them is definitely something to consider.