Block Tokens are perfectly fine for tribute monster fodder.
Remember that any limitations on how Tokens can be used are always explained in the effects that generate them (or some cards that say you can't use Tokens for their effects); Scapegoat says Sheep Tokens can't be used for Tribute Summons/Sets, Blockman says Block Tokens can't declare an attack, etc. But other than what token generating cards specifically say you can't do with tokens, you can use them for just about any other purpose.
