No, they are not. [I assume you are talking about the buyer getting cash from the exercise]. They are a liability on a buyout.
Let us for example say NWBO has 500M shares out, and 500M warrants at $.30, and the offer is for $4/share.
W/o the warrants, that would cost the buyer $2B.
With the warrants, it costs the buyer $3.4B
In reality, the buyer would not care about the share price, just what they pay. Thus what you would see is a buyer who wants to offer $2B for the company would pay $4/s w/o warrants, but only $2.15/s with them.
Warrants NEVER have a positive value for the party that sold them. If they did, why not just pass out warrants for free?