Spooner fails dramatically on Intellectual Property?

THE LAW OF INTELLECTUAL PROPERTY;
OR AN ESSAY ON THE RIGHT OF AUTHORS AND INVENTORS TO A PERPETUAL PROPERTY IN THEIR IDEAS.

http://lysanderspooner.org/intellect/contents.htm

He says “to use another’s property, without his consent, is to violate his right of property; because it is for the time being, assuming a dominion over wealth”. For IP this is not true. Ideas aren’t scarce and if I can discover an idea by observing someone else or invent it myself then I literally haven’t done anything to another person’s property. He says “for the time being”, clearly to denote that you’re taking something away from somebody else, i.e. that the other person cannot use it for that time. When we move beyond scarce property and into ideas this stops being true altogether.