If You have a command in Your podbot.cfg
pb add 100 [and also other parameters]
then the bot will be added with the skill 100 - because You asked for it by specyfing the skill in the command for adding bots. The min/max botskill parameters are used in the case if You don't clearly specify the skill the bot should come to the server - like this:
pb add
in this case there is a bot added with a random skill between pb_minbotskill and pb_maxbotskill parameters.
So the behaviour of bots coming with a skill 100 in Your case is not a bug.
Use
this plugin - it wll follow for You the restriction done for players by standard restmenu plugin.