Nowhere does is say they are weighting the EU and local elections over the 17 GE, it says they use MRP polling and constituency level demographics to predict how people will vote in each constituency, then make a recommendation based on the positions of the candidates in each one as to who you should vote for.
without seeing what you're talking about I can't comment, but if it's as transparent as Owen Jones' attempt then it's most probably bollocks. From what I've seen Owen spends about 95% of his time attacking Lib Dems and ex Labour MPs on twitter rather than going after the Tories or Farage, he's pretty obsessed tbh.
taking 2 of those:
Given the way things have changed since 2017 with the Lib Dem revival in the polls and the way Brexit has developed I'd say it's more than possible the Lib Dems are the most likely to beat the Tories in these seats, and alot of others too.
read this thread, the comments and her replies for a better understanding of it.