variable names could be too long

A flag for each content type is saved as a variable to tell if the abuse module applies to that content type or not. The variable name is formed like: "abuse_content_node_type_" + <node-type-name>

Node type names could be 32 characters long and as a result potentially variable names could be 32 + 24 (the length of "abuse_content_node_type_") = 56

This will result in errors since variable names are limited to 48 characters. And these errors are very confusing.

Had the exact same issue with the Auto Expire and Maxlength modules.

You need to limit the variable name prefix to 48 - 32 = 16 characters, for example "abuse_c_nt_". Also, in the .install file you probably want to provide an upgrade function. Have a look at the two modules mentioned above for samples.