He's not interfering with any normal operation of any system. He is offering links. You can follow them or not, entirely at your own discretion. Those links load slowly. You can wait for them to complete or not, entirely at your own discretion.

The crawler's normal operation is not interfered with in any way: the crawler does exactly what it's programmed to do. If its programmers decided it should exhaustively follow links, he's not preventing it from doing that operation.

Legally, at best you'd be looking to warp the concept of attractive nuisance to apply to a crawler. As that legal concept is generally intended to prevent bodily harm to children, however, good luck.