one wonders what the more established operators think of Ryanair
That's a bit of a wishy-washy statement. What do you mean by 'more established' operators?
I can't really see the commercial basis for an airline to pick up those routes from LPL just because FR have moved them half hour down the road to MAN (and in several cases with a much higher frequency). Broadly speaking, LPL and MAN serve a fairly similar catchment and any duplicate routes from LPL would still compete with those FR routes now at MAN very strongly.
Goes without saying FR clearly have some sort of very attractive deal with MAG, not just at MAN but across all their airports. That's most likely if anything where their main incentive comes from. BTS specifically may be a response to LS and EZY on VIE?